Compounds and methods for the detection and prevention of T.cruzi infection

ABSTRACT

Compounds and methods are provided for diagnosing  Trypanosoma cruzi  infection. The disclosed compounds are polypeptides, or antibodies thereto, that contain one or more epitopes of  T. cruzi  antigens. The compounds are useful in a variety of immunoassays for detecting  T. cruzi  infection. The polypeptide compounds are further useful in vaccines and pharmaceutical compositions for inducing protective immunity against Chagas&#39; disease in individuals exposed to  T. cruzi.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No. 08/993,674, filed Dec. 18, 1997, which is a continuation-in-part of U.S. application Ser. No. 08/834,306, filed Apr. 15, 1997, now U.S. Pat. No. 6,054,135, which claims priority from PCT Application No. PCT/US96/18624, filed Nov. 14, 1996, which claims priority from U.S. application Ser. No. 08/557,309, now U.S. Pat. No. 5,916,572, filed Nov. 14, 1995.

TECHNICAL FIELD

The present invention relates generally to the diagnosis of T. cruzi infection. The invention is more particularly related to the use of one or more T. cruzi antigenic peptides, or antibodies thereto, in methods and diagnostic kits to screen individuals and blood supplies for T. cruzi infection. The invention is also directed to vaccine compositions for immunizing an individual to prevent Chagas' disease.

BACKGROUND OF THE INVENTION

Protozoan parasites are a serious health threat in many areas of the world. Trypanosoma cruzi (T. cruzi) is one such parasite that infects millions of individuals, primarily in Central and South America. Infections with this parasite can cause Chagas' disease, which may result in chronic heart disease and a variety of immune system disorders. It is estimated that 18 million people in Latin America are infected with T. cruzi, but there is no reliable treatment for the clinical manifestations of infection. No vaccine for the prevention of Chagas' disease is currently available.

The most significant route of transmission in areas where the disease is endemic is through contact with an infected triatomid bug. In other areas, however, blood transfusions are the dominant means of transmission. To inhibit the transmission of T. cruzi in such regions, it is necessary to develop accurate methods for diagnosing T. cruzi infection in individuals and for screening blood supplies. Blood bank screening is particularly important in South America, where 0.1%-62% of samples may be infected and where the parasite is frequently transmitted by blood transfusion. There is also increasing concern that the blood supply in certain U.S. cities may be contaminated with T. cruzi parasites.

The diagnosis of T. cruzi infection has been problematic, since accurate methods for detecting the parasite that are suitable for routine use have been unavailable. During the acute phase of infection, which may last for decades, the infection may remain quiescent and the host may be asymptomatic. As a result, serological tests for T. cruzi infection are the most reliable and the most commonly used.

Such diagnoses are complicated, however, by the complex life cycle of the parasite and the diverse immune responses of the host. The parasite passes through an epimastigote stage in the insect vector and two main stages in the mammalian host. One host stage is present in blood (the trypomastigote stage) and a second stage is intracellular (the amastigote stage). The multiple stages result in a diversity of antigens presented by the parasite during infection. In addition, immune responses to protozoan infection are complex, involving both humoral and cell-mediated responses to the array of parasite antigens.

While detecting antibodies against parasite antigens is the most common and reliable method of diagnosing clinical and subclinical infections, current tests are expensive and difficult. Most serological tests use whole or lysed T. cruzi and require positive results on two of three tests, including complement fixation, indirect immunofluorescence, passive agglutination or ELISA, to accurately detect T. cruzi infection. The cost and difficulty of such tests has prevented the screening of blood or sera in many endemic areas.

Accordingly, there is a need in the art for more specific and sensitive methods of detecting T. cruzi infections in blood supplies and individuals. The present invention fulfills these needs and further provides other related advantages.

SUMMARY OF THE INVENTION

Briefly stated, this invention provides compounds and methods for detecting and protecting against T. cruzi infection in individuals and in blood supplies, and for screening for T. cruzi infection in biological samples. In one aspect, the present invention provides methods for detecting T. cruzi infection in a biological sample, comprising (a) contacting the biological sample with a polypeptide comprising an epitope of a T. cruzi antigen having an amino acid sequence encoded by a nucleotide sequence recited in SEQ ID NO:1-SEQ ID NO:22, or a variant of such an antigen that differs only in conservative substitutions and/or modifications; and (b) detecting in the biological sample the presence of antibodies that bind to the polypeptide, therefrom detecting T. cruzi infection in the biological sample.

In another aspect of this invention, polypeptides are provided comprising an epitope of a T. cruzi antigen having an amino acid sequence encoded by a nucleotide sequence recited in SEQ ID NO:1-SEQ ID NO:21, or a variant of such an antigen that differs only in conservative substitutions and/or modifications.

Within related aspects, DNA sequences encoding the above polypeptides, expression vectors comprising these DNA sequences and host cells transformed or transfected with such expression vectors are also provided.

In another aspect, the present invention provides diagnostic kits for detecting T. cruzi infection in a biological sample, comprising (a) a polypeptide comprising an epitope of a T. cruzi antigen having an amino acid sequence encoded by a nucleotide sequence recited in SEQ ID NO:1-SEQ ID NO:22, or a variant of such an antigen that differs only in conservative substitutions and/or modifications; and (b) a detection reagent.

In yet another aspect of the invention, methods for detecting the presence of T. cruzi infection in a biological sample are provided, comprising (a) contacting a biological sample with a monoclonal antibody that binds to an epitope of a T. cruzi antigen having an amino acid sequence encoded by a nucleotide sequence recited in SEQ ID NO:1-SEQ ID NO:22, or a variant of such an antigen that differs only in conservative substitutions and/or modifications; and (b) detecting in the biological sample the presence of T. cruzi parasites that bind to the monoclonal antibody.

Within related aspects, pharmaceutical compositions comprising the above polypeptides and a physiologically acceptable carrier, and vaccines comprising the above polypeptides in combination with an adjuvant, are also provided.

The present invention also provides, within other aspects, methods for inducing protective immunity against Chagas' disease in a patient, comprising administering to a patient a pharmaceutical composition or vaccine as described above.

Within other aspects, the present invention provides methods for detecting T. cruzi infection in a biological sample, comprising (a) contacting the biological sample with a first polypeptide comprising an epitope of a T. cruzi antigen having an amino acid sequence encoded by a nucleotide sequence recited in SEQ ID NO:1-SEQ ID NO:22, or a variant of said antigen that differs only in conservative substitutions and/or modifications; (b) contacting the biological sample with one or more additional polypeptides comprising one or more epitopes of other T. cruzi antigens, or a variant thereof that differs only in conservative substitutions and/or modifications; and (c) detecting in the biological sample the presence of antibodies that bind to one or more of said polypeptides, therefrom detecting T. cruzi infection in the biological sample. In one embodiment, the additional polypeptide comprises an epitope of TcD, or a variant thereof that differs only in conservative substitutions and/or modifications. In another embodiment, the additional polypeptides comprise an epitope of TcD (or a variant thereof that differs only in conservative substitutions and/or modifications) and an epitope of TcE (or a variant thereof that differs only in conservative substitutions and/or modifications). In yet another embodiment, the additional polypeptides comprise an epitope of TcD (or a variant thereof that differs only in conservative substitutions and/or modifications) and PEP-2 (or a variant thereof that differs only in conservative substitutions and/or modifications).

In yet further aspects, the present invention provides combination polypeptides comprising two or more polypeptides, each polypeptide comprising an epitope of a T. cruzi antigen having an amino acid sequence encoded by a nucleotide sequence recited in SEQ ID NO:1-SEQ ID NO:22, or a variant thereof that differs only in conservative substitutions and/or modifications. Combination polypeptides comprising at least one epitope of a T. cruzi antigen having an amino acid sequence encoded by a nucleotide sequence recited in SEQ ID NO:1-SEQ ID NO:22, or a variant thereof that differs only in conservative substitutions and/or modifications, and at least one epitope selected from the group consisting of TcD epitopes, TcE epitopes, PEP-2 epitopes and variants thereof that differ only in conservative substitutions and/or modifications are also provided. In specific embodiments, combination polypeptides comprising an amino acid sequence of SEQ ID NO:82 or 95 are provided. Such combination polypeptides may be prepared either by synthetic means or using recombinant DNA technology.

In related aspects, methods are provided for detecting T. cruzi infection in a biological sample, comprising (a) contacting the biological sample with at least one of the above combination polypeptides and (b) detecting in the biological sample the presence of antibodies that bind to the combination polypeptide.

These and other aspects of the present invention will become apparent upon reference to the following detailed description and attached drawings. All references disclosed herein are hereby incorporated by reference in their entirety as if each was incorporated individually.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph comparing the reactivity of T. cruzi lysate and a representative polypeptide of the present invention (rTcc6) in an ELISA assay performed using sera from T. cruzi-infected (Pos) and uninfected (Neg) individuals. The bars represent±1 standard deviation.

FIG. 2 is a graph presenting a comparison of the reactivity of representative polypeptides of the subject invention in an ELISA assay performed using sera from T. cruzi-infected (Pos) and uninfected (Neg) individuals. Experiment 1 shows a comparison of rTcc22 and the peptides Tcc22-1 and Tcc22-1+; Experiment 2 shows a comparison of rTcc22, rTcHi12 and the peptides Tcc22-1, Tcc22-1+ and Tcc22-2.1. The bars represent±1 standard deviation.

FIG. 3 is a graph depicting a comparison of the reactivity of T. cruzi lysate and a representative polypeptide (Tcc38) in an ELISA assay performed using sera from T. cruzi-infected (Pos) and uninfected (Neg) individuals, as well as using sera from individuals with visceral leishmaniasis (VL), cutaneous leishmaniasis (CL), tuberculosis (TB) and malaria. The bars represent±1 standard deviation.

FIG. 4 is a graph presenting a comparison of the reactivity of T. cruzi lysate and several polypeptides of the present invention, representing different reading frames of the TcLo1 and TcHi10 antigens, in an ELISA assay performed using sera from T. cruzi-infected (Pos) and uninfected (Neg) individuals. The bars represent±1 standard deviation.

FIG. 5 is a graph comparing the reactivity of T. cruzi lysate and a representative polypeptide (TccLo1.2) in an ELISA assay performed using sera from T. cruzi-infected (Pos) and uninfected (Neg) individuals, as well as sera from individuals with visceral leishmaniasis (VL), cutaneous leishmaniasis (CL), malaria and tuberculosis (TB).

FIG. 6 is a graph depicting the ELISA reactivity of a series of polypeptide combinations with T. cruzi positive and negative sera.

FIG. 7 is a graph presenting the ELISA reactivity of a series of TcE polypeptide variants with T. cruzi positive and negative sera.

FIG. 8 is a graph comparing the ELISA reactivity of two dipeptides, a tripeptide and a tetrapeptide of the present invention with T. cruzi positive and negative sera.

FIG. 9 is a graph presenting the ELISA reactivity of a representative polypeptide of the present invention (TcHi29) and of TcE with sera from normal individuals, T. cruzi patients, and patients with other diseases.

FIG. 10 is a graph comparing the ELISA reactivity of two representative dipeptide mixtures with T. cruzi positive and negative sera, one mixture including a TcE epitope and the other including a TcHi29 epitope of the present invention.

FIG. 11 is a graph comparing the ELISA reactivity of the recombinant fusion polypeptide TcF with sera from T. cruzi patients and from normal donors with the reactivity of the synthetic branched tetrapeptide 2/D/E/Lo1.2.

DETAILED DESCRIPTION OF THE INVENTION

As noted above, the present invention is generally directed to compounds and methods for detecting and protecting against T. cruzi infection in individuals and in blood supplies. The compounds of this invention generally comprise one or more epitopes of T. cruzi antigens. In particular, polypeptides comprising an epitope of a T. cruzi antigen having an amino acid sequence encoded by a nucleotide sequence recited in SEQ ID NO:1-SEQ ID NO:22 are preferred. As used herein, the term “polypeptide” encompasses amino acid chains of any length, including full length (i.e., native) antigens. Thus, a polypeptide comprising an epitope may consist entirely of the epitope or may contain additional sequences. The additional sequences may be derived from the native antigen or may be heterologous, and such sequences may (but need not) be antigenic. A protein “having” a particular amino acid sequence is a protein that contains, within its full length sequence, the recited sequence. Such a protein may, or may not, contain additional amino acid sequence. The use of one or more epitopes from additional T. cruzi proteins, prior to or in combination with one or more epitopes of sequences recited herein, to enhance the sensitivity and specificity of the diagnosis, is also contemplated.

An “epitope,” as used herein, is a portion of a T. cruzi antigen that reacts with sera from T. cruzi-infected individuals (i.e., an epitope is specifically bound by one or more antibodies within such sera). Epitopes of the antigens described in the present application may generally be identified using methods known to those of ordinary skill in the art, such as those summarized in Paul, Fundamental Immunology, 3rd ed., 243-247 (Raven Press, 1993) and references cited therein. For example, a polypeptide derived from a native T. cruzi antigen may be screened for the ability to react with pooled sera obtained from T. cruzi-infected patients. Suitable assays for evaluating reactivity with T. cruzi-infected sera, such as an enzyme linked immunosorbent assay (ELISA), are described in more detail below, and in Harlow and Lane, Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, 1988. An epitope of a polypeptide is a portion that reacts with such antisera at a level that is substantially similar to the reactivity of the full length polypeptide. In other words, an epitope may generate at least about 80%, and preferably at least about 100%, of the response generated by the full length polypeptide in an antibody binding assay (e.g., an ELISA).

The compounds and methods of this invention also encompass variants of the above polypeptides. A polypeptide “variant,” as used herein, is a polypeptide that differs from the recited polypeptide only in conservative substitutions and/or modifications, such that the antigenic properties of the polypeptide are retained. In a preferred embodiment, variant polypeptides differ from an identified sequence by substitution, deletion or addition of five amino acids or fewer. Such variants may generally be identified by modifying one of the above polypeptide sequences, and evaluating the antigenic properties of the modified polypeptide using, for example, the representative procedures described herein. Polypeptide variants preferably exhibit at least about 70%, more preferably at least about 90% and most preferably at least about 95% identity (determined as described below) to the identified polypeptides.

As used herein, a “conservative substitution” is one in which an amino acid is substituted for another amino acid that has similar properties, such that one skilled in the art of peptide chemistry would expect the secondary structure and hydropathic nature of the polypeptide to be substantially unchanged. In general, the following groups of amino acids represent conservative changes: (1) ala, pro, gly, glu, asp, gln, asn, ser, thr; (2) cys, ser, tyr, thr; (3) val, ile, leu, met, ala, phe; (4) lys, arg, his; and (5) phe, tyr, trp, his.

Variants may also, or alternatively, contain other modifications, including the deletion or addition of amino acids that have minimal influence on the antigenic properties, secondary structure and hydropathic nature of the polypeptide. For example, a polypeptide may be conjugated to a signal (or leader) sequence at the N-terminal end of the protein which co-translationally or post-translationally directs transfer of the protein. The polypeptide may also be conjugated to a linker or other sequence for ease of synthesis, purification or identification of the polypeptide (e.g., poly-His), or to enhance binding of the polypeptide to a solid support. For example, a polypeptide may be conjugated to an immunoglobulin Fc region.

A nucleotide “variant” is a sequence that differs from the recited nucleotide sequence in having one or more nucleotide deletions, substitutions or additions. Such modifications may be readily introduced using standard mutagenesis techniques, such as oligonucleotide-directed site-specific mutagenesis as taught, for example, by Adelman et al. (DNA, 2:183, 1983). Nucleotide variants may be naturally occurring allelic variants, or non-naturally occurring variants. Variant nucleotide sequences preferably exhibit at least about 70%, more preferably at least about 80% and most preferably at least about 90% identity (determined as described below) to the recited sequence.

The polypeptides provided by the present invention include variants that are encoded by DNA sequences which are substantially homologous to one or more of the DNA sequences specifically recited herein. “Substantial homology,” as used herein, refers to DNA sequences that are capable of hybridizing under moderately stringent conditions. Suitable moderately stringent conditions include prewashing in a solution of 5×SSC, 0.5% SDS, 1.0 mM EDTA (pH 8.0); hybridizing at 50° C.-65° C., 5×SSC, overnight or, in the event of cross-species homology, at 45° C. with 0.5×SSC; followed by washing twice at 65° C. for 20 minutes with each of 2×, 0.5× and 0.2× SSC containing 0.1% SDS. Such hybridizing DNA sequences are also within the scope of this invention, as are nucleotide sequences that, due to code degeneracy, encode an immunogenic polypeptide that is encoded by a hybridizing DNA sequence.

Two nucleotide or polypeptide sequences are said to be “identical” if the sequence of nucleotides or amino acid residues in the two sequences is the same when aligned for maximum correspondence as described below. Comparisons between two sequences are typically performed by comparing the sequences over a comparison window to identify and compare local regions of sequence similarity. A “comparison window” as used herein, refers to a segment of at least about 20 contiguous positions, usually 30 to about 75, 40 to about 50, in which a sequence may be compared to a reference sequence of the same number of contiguous positions after the two sequences are optimally aligned.

Optimal alignment of sequences for comparison may be conducted using the Megalign program in the Lasergene suite of bioinformatics software (DNASTAR, Inc., Madison, Wis.), using default parameters. This program embodies several alignment schemes described in the following references: Dayhoff, M.O. (1978) A model of evolutionary change in proteins—Matrices for detecting distant relationships. In Dayhoff, M.O. (ed.) Atlas of Protein Sequence and Structure, National Biomedical Research Foundation, Washington D.C. Vol. 5, Suppl. 3, pp. 345-358; Hein J. (1990) Unified Approach to Alignment and Phylogenes pp. 626-645 Methods in Enzymology vol. 183, Academic Press, Inc., San Diego, Calif.; Higgins, D. G. and Sharp, P. M. (1989) Fast and sensitive multiple sequence alignments on a microcomputer CABIOS 5:151-153; Myers, E. W. and Muller W. (1988) Optimal alignments in linear space CABIOS 4:11-17; Robinson, E. D. (1971) Comb. Theor 11:105; Santou, N. Nes, M. (1987). The neighbor joining method. A new method for reconstructing phylogenetic trees Mol. Biol. Evol. 4:406-425; Sneath, P. H. A. and Sokal, R. R. (1973) Numerical Taxonomy—the Principles and Practice of Numerical Taxonomy, Freeman Press, San Francisco, Calif. ; Wilbur, W. J. and Lipman, D. J. (1983) Rapid similarity searches of nucleic acid and protein data banks Proc. Natl. Acad, Sci. USA 80:726-730.

Preferably, the “percentage of sequence identity” is determined by comparing two optimally aligned sequences over a window of comparison of at least 20 positions, wherein the portion of the polynucleotide sequence in the comparison window may comprise additions or deletions (i.e. gaps) of 20 percent or less, usually 5 to 15 percent, or 10 to 12 percent, as compared to the reference sequences (which does not comprise additions or deletions) for optimal alignment of the two sequences. The percentage is calculated by determining the number of positions at which the identical nucleic acid bases or amino acid residue occurs in both sequences to yield the number of matched positions, dividing the number of matched positions by the total number of positions in the reference sequence (i.e. the window size) and multiplying the results by 100 to yield the percentage of sequence identity.

In a related aspect, combination polypeptides comprising epitopes of multiple T. cruzi antigens are disclosed. A “combination polypeptide” is a polypeptide in which epitopes of different T. cruzi antigens, or variants thereof, are joined, for example through a peptide linkage, into a single amino acid chain. The amino acid chain thus formed may be either linear or branched. The epitopes may be joined directly (i.e., with no intervening amino acids) or may be joined by way of a linker sequence (e.g., Gly-Cys-Gly) that does not significantly alter the antigenic properties of the epitopes. The peptide epitopes may also be linked through non-peptide linkages, such as hetero- or homo-bifunctional agents that chemically or photochemically couple between specific functional groups on the peptide epitopes such as through amino, carboxyl, or sulthydryl groups. Bifunctional agents which may be usefully employed in the combination polypeptides of the present invention are well known to those of skill in the art. Epitopes may also be linked by means of a complementary ligand/anti-ligand pair, such as avidin/biotin, with one or more epitopes being linked to a first member of the ligand/anti-ligand pair and then being bound to the complementary member of the ligand/anti-ligand pair either in solution or in solid phase. A combination polypeptide may contain multiple epitopes of polypeptides as described herein and/or may contain epitopes of one or more other T. cruzi antigens, such as TcD, TcE or PEP-2, linked to an epitope described herein.

In general, T. cruzi antigens, and DNA sequences encoding such antigens, may be prepared using any of a variety of procedures. For example, a T. cruzi cDNA or genomic DNA expression library may be screened with pools of sera from T. cruzi-infected individuals. Such screens may generally be performed using techniques well known to those of ordinary skill in the art, such as those described in Sambrook et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratories, Cold Spring Harbor, N.Y., 1989. Briefly, the bacteriophage library may be plated and transferred to filters. The filters may then be incubated with serum and a detection reagent. In the context of this invention, a “detection reagent” is any compound capable of binding to the antibody-antigen complex, which may then be detected by any of a variety of means known to those of ordinary skill in the art. Typical detection reagents for screening purposes contain a “binding agent,” such as Protein A, Protein G, IgG or a lectin, coupled to a reporter group. Preferred reporter groups include, but are not limited to, enzymes, substrates, cofactors, inhibitors, dyes, radionuclides, luminescent groups, fluorescent groups and biotin. More preferably, the reporter group is horseradish peroxidase, which may be detected by incubation with a substrate such as tetramethylbenzidine or 2,2′-azino-di-3-ethylbenzthiazoline sulfonic acid. Plaques containing cDNAs that express a protein that binds to an antibody in the serum may be isolated and purified by techniques known to those of ordinary skill in the art. Appropriate methods may be found, for example, in Sambrook et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratories, Cold Spring Harbor, N.Y., 1989.

DNA molecules having the nucleotide sequences recited in SEQ ID NO:1-SEQ ID NO:18 may be isolated by screening a T. cruzi genomic expression library with pools of sera from T. cruzi-infected individuals, as described above. More specifically, DNA molecules having the nucleotide sequences recited in SEQ ID NO:1-SEQ ID NO:16 may be isolated by screening the library with a pool of sera that displays serological reactivity (in an ELISA or Western assay) with parasite lysate and/or one or both of the T. cruzi antigens TcD and TcE, described in U.S. Pat. No. 5,304,371 and U.S. Ser. No. 08/403,379, filed Mar. 14, 1995. A subsequent screen is then performed with patient sera lacking detectable anti-TcD antibody. A DNA molecule having the nucleotide sequences recited in SEQ ID NO:17 (5′ end) and SEQ ID NO:18 (3′ end) may be isolated by screening the genomic expression library with a pool of sera that displays lower serological reactivity (i.e., detects a signal less than 3 standard deviations over background reactivity in an ELISA or Western assay) with lysate, TcD and TcE, followed by a subsequent screen with patient sera lacking detectable anti-TcD antibody.

DNA molecules having the sequences recited in SEQ ID NO:19-SEQ ID NO:22 may be obtained by screening an unamplified T. cruzi cDNA expression library with sera (both higher and lower serological reactivity) from T. cruzi-infected individuals, as described above.

Alternatively, DNA molecules having the sequences recited in SEQ ID NO:1-SEQ ID NO:22 may be amplified from T. cruzi genomic DNA or cDNA via polymerase chain reaction. For this approach, sequence-specific primers may be designed based on the sequences provided in SEQ ID NO:1-SEQ ID NO:22, and may be purchased or synthesized. An amplified portion of the DNA sequences may then be used to isolate the full length genomic or cDNA clones using well known techniques, such as those described in Sambrook et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratories, Cold Spring Harbor, N.Y. (1989).

Epitopes of antigens having amino acid sequences encoded by the above DNA sequences may generally be identified by generating polypeptides containing portions of the native antigen and evaluating the reactivity of the polypeptides with sera from T. cruzi-infected individuals, as described above. In many instances, peptides comprising one or more repeat sequences found in the native antigen contain an epitope. Such repeat sequences may be identified based on inspection of the above nucleotide sequences. Representative repeat sequences for antigens encoded by the above DNA sequences are provided in SEQ ID NO:23-SEQ ID NO:36 and SEQ ID NO:47-SEQ ID NO:49. More specifically, repeat sequences for the sequence recited in SEQ ID NO:3 are provided in SEQ ID NO:23 (Frame 1), SEQ ID NO:24 (Frame 2) and SEQ ID NO:25 (Frame 3). Repeat sequences for the sequence recited in SEQ ID NO:4 are provided in SEQ ID NO:26 (Frame 1) and SEQ ID NO:27 (Frame 3) and repeat sequences for SEQ ID NO:9 are provided in SEQ ID NO:47 (Frame 1), SEQ ID NO:48 (Frame 2) and SEQ ID NO:49 (Frame 3). For SEQ ID NO:12, repeat sequences are provided in SEQ ID NO:28 (Frame 1), SEQ ID NO:29 (Frame 2) and SEQ ID NO:30 (Frame 3). SEQ ID NO:31 recites a repeat sequence for SEQ ID NO:15. For SEQ ID NO:16, repeat sequences are provided in SEQ ID NO:32 (Frame 2) and SEQ ID NO:33 (Frame 3). Finally, repeat sequences for SEQ ID NO:18 are provided in SEQ ID NO:34 (Frame 1), SEQ ID NO:35 (Frame 2) and SEQ ID NO:36 (Frame 3).

The polypeptides described herein may be generated using techniques well known to those of ordinary skill in the art. Polypeptides having fewer than about 100 amino acids, and generally fewer than about 50 amino acids, can be synthesized using, for example, the Merrifield solid-phase synthesis method, where amino acids are sequentially added to a growing amino acid chain. See Merrifield, J. Am. Chem. Soc. 85:2149-2146, 1963. Equipment for automated synthesis of polypeptides is commercially available from suppliers such as Perkin Elmer/Applied Biosystems Division, Foster City, Calif. Thus, for example, polypeptides comprising the above repeat sequences or portions thereof, may be synthesized by this method. Similarly, epitopes of other native antigens, or variants thereof, may be prepared using an automated synthesizer.

Alternatively, the polypeptides of this invention may be prepared by expression of recombinant DNA encoding the polypeptide in cultured host cells. Preferably, the host cells are E. coli, yeast, an insect cell line (such as Spodoptera or Trichoplusia) or a mammalian cell line, including (but not limited to) CHO, COS and NS-1. The DNA sequences expressed in this manner may encode naturally occurring proteins, such as full length antigens having the amino acid sequences encoded by the DNA sequences of SEQ ID NO:1-SEQ ID NO:22, portions of naturally occurring proteins, or variants of such proteins. Representative polypeptides encoded by such DNA sequences are provided in SEQ ID NO:37-SEQ ID NO:46, SEQ ID NO:52, and SEQ ID NO:65.

Expressed polypeptides of this invention are generally isolated in substantially pure form. Preferably, the polypeptides are isolated to a purity of at least 80% by weight, more preferably, to a purity of at least 95% by weight, and most preferably to a purity of at least 99% by weight. In general, such purification may be achieved using, for example, the standard techniques of ammonium sulfate fractionation, SDS-PAGE electrophoresis, and affinity chromatography.

In another aspect of this invention, methods for detecting T. cruzi infection in individuals and blood supplies are disclosed. In one embodiment, T. cruzi infection may be detected in any biological sample that contains antibodies. Preferably, the sample is blood, serum, plasma, saliva, cerebrospinal fluid or urine. More preferably, the sample is a blood or serum sample obtained from a patient or a blood supply. Briefly, T. cruzi infection may be detected using any one or more of the polypeptides described above, or variants thereof, to determine the presence or absence of antibodies to the polypeptide or polypeptides in the sample, relative to a predetermined cut-off value.

There are a variety of assay formats known to those of ordinary skill in the art for using purified antigen to detect antibodies in a sample. See, e.g., Harlow and Lane, Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, 1988. In a preferred embodiment, the assay involves the use of polypeptide immobilized on a solid support to bind to and remove the antibody from the sample. The bound antibody may then be detected using a detection reagent that binds to the antibody/peptide complex and contains a detectable reporter group. Suitable detection reagents include antibodies that bind to the antibody/polypeptide complex and free polypeptide labeled with a reporter group (e.g., in a semi-competitive assay). Alternatively, a competitive assay may be utilized, in which an antibody that binds to the polypeptide is labeled with a reporter group and allowed to bind to the immobilized antigen after incubation of the antigen with the sample. The extent to which components of the sample inhibit the binding of the labeled antibody to the polypeptide is indicative of the reactivity of the sample with the immobilized polypeptide.

The solid support may be any solid material known to those of ordinary skill in the art to which the antigen may be attached. For example, the solid support may be a test well in a microtiter plate or a nitrocellulose or other suitable membrane. Alternatively, the support may be a bead or disc, such as glass, fiberglass, latex or a plastic material such as polystyrene or polyvinylchloride. The support may also be a magnetic particle or a fiber optic sensor, such as those disclosed, for example, in U.S. Pat. No. 5,359,681.

The polypeptide may be bound to the solid support using a variety of techniques known to those in the art, which are amply described in the patent and scientific literature. In the context of the present invention, the term “bound” refers to both noncovalent association, such as adsorption, and covalent attachment (which may be a direct linkage between the antigen and functional groups on the support or may be a linkage by way of a cross-linking agent). Binding by adsorption to a well in a microtiter plate or to a membrane is preferred. In such cases, adsorption may be achieved by contacting the polypeptide, in a suitable buffer, with the solid support for a suitable amount of time. The contact time varies with temperature, but is typically between about 1 hour and 1 day. In general, contacting a well of a plastic microtiter plate (such as polystyrene or polyvinylchloride) with an amount of polypeptide ranging from about 10 ng to about 1 μg, and preferably about 100 ng, is sufficient to bind an adequate amount of antigen. Nitrocellulose will bind approximately 100 μg of protein per cm³.

Covalent attachment of polypeptide to a solid support may generally be achieved by first reacting the support with a bifunctional reagent that will react with both the support and a functional group, such as a hydroxyl or amino group, on the polypeptide. For example, the polypeptide may be bound to supports having an appropriate polymer coating using benzoquinone or by condensation of an aldehyde group on the support with an amine and an active hydrogen on the polypeptide (see, e.g., Pierce Immunotechnology Catalog and Handbook (1991) at A12-A13).

In certain embodiments, the assay is an enzyme linked immunosorbent assay (ELISA). This assay may be performed by first contacting a polypeptide antigen that has been immobilized on a solid support, commonly the well of a microtiter plate, with the sample, such that antibodies to the polypeptide within the sample are allowed to bind to the immobilized polypeptide. Unbound sample is then removed from the immobilized polypeptide and a detection reagent capable of binding to the immobilized antibody-polypeptide complex is added. The amount of detection reagent that remains bound to the solid support is then determined using a method appropriate for the specific detection reagent.

Once the polypeptide is immobilized on the support, the remaining protein binding sites on the support are typically blocked. Any suitable blocking agent known to those of ordinary skill in the art, such as bovine serum albumin or Tween 20™ (Sigma Chemical Co., St. Louis, Mo.). The immobilized polypeptide is then incubated with the sample, and antibody (if present in the sample) is allowed to bind to the antigen. The sample may be diluted with a suitable diluent, such as phosphate-buffered saline (PBS) prior to incubation. In general, an appropriate contact time (i.e., incubation time) is that period of time that is sufficient to permit detect the presence of T. cruzi antibody within a T. cruzi-infected sample. Preferably, the contact time is sufficient to achieve a level of binding that is at least 95% of that achieved at equilibrium between bound and unbound antibody. Those of ordinary skill in the art will recognize that the time necessary to achieve equilibrium may be readily determined by assaying the level of binding that occurs over a period of time. At room temperature, an incubation time of about 30 minutes is generally sufficient.

Unbound sample may then be removed by washing the solid support with an appropriate buffer, such as PBS containing 0.1% Tween 20™. Detection reagent may then be added to the solid support. An appropriate detection reagent is any compound that binds to the immobilized antibody-polypeptide complex and that can be detected by any of a variety of means known to those in the art. Preferably, the detection reagent contains a binding agent (such as, for example, Protein A, Protein G, immunoglobulin, lectin or free antigen) conjugated to a reporter group. Preferred reporter groups include enzymes (such as horseradish peroxidase), substrates, cofactors, inhibitors, dyes, radionuclides, luminescent groups, fluorescent groups and biotin. The conjugation of binding agent to reporter group may be achieved using standard methods known to those of ordinary skill in the art. Common binding agents may also be purchased conjugated to a variety of reporter groups from many sources (e.g., Zymed Laboratories, San Francisco, Calif. and Pierce, Rockford, Ill.).

The detection reagent is then incubated with the immobilized antibody-polypeptide complex for an amount of time sufficient to detect the bound antibody. An appropriate amount of time may generally be determined from the manufacturer's instructions or by assaying the level of binding that occurs over a period of time. Unbound detection reagent is then removed and bound detection reagent is detected using the reporter group. The method employed for detecting the reporter group depends upon the nature of the reporter group. For radioactive groups, scintillation counting or autoradiographic methods are generally appropriate. Spectroscopic methods may be used to detect dyes, luminescent groups and fluorescent groups. Biotin may be detected using avidin, coupled to a different reporter group (commonly a radioactive or fluorescent group or an enzyme). Enzyme reporter groups may generally be detected by the addition of substrate (generally for a specific period of time), followed by spectroscopic or other analysis of the reaction products.

To determine the presence or absence of T. cruzi antibodies in the sample, the signal detected from the reporter group that remains bound to the solid support is generally compared to a signal that corresponds to a predetermined cut-off value. This cut-off value is preferably the average mean signal obtained when the immobilized antigen is incubated with samples from an uninfected patient. In general, a sample generating a signal that is three standard deviations above the mean is considered positive for T. cruzi antibodies and T. cruzi infection. In an alternate preferred embodiment, the cut-off value is determined using a Receiver Operator Curve, according to the method of Sackett et al., Clinical Epidemiology: A Basic Science for Clinical Medicine, p. 106-7 (Little Brown and Co., 1985). Briefly, in this embodiment, the cut-off value may be determined from a plot of pairs of true positive rates (i.e., sensitivity) and false positive rates (100%-specificity) that correspond to each possible cut-off value for the diagnostic test result. The cut-off value on the plot that is the closest to the upper left-hand corner (i.e., the value that encloses the largest area) is the most accurate cut-off value, and a sample generating a signal that is higher than the cut-off value determined by this method may be considered positive.

Alternatively, the cut-off value may be shifted to the left along the plot, to minimize the false positive rate, or to the right, to minimize the false negative rate. In general, a sample generating a signal that is higher than the cut-off value determined by this method is considered positive for T. cruzi infection.

In a related embodiment, the assay is performed in a flow-through or strip test format, wherein the antigen is immobilized on a membrane such as nitrocellulose. In the flow-through test, antibodies within the sample bind to the immobilized polypeptide as the sample passes through the membrane. A detection reagent (e.g., protein A-colloidal gold) then binds to the antibody-polypeptide complex as the solution containing the detection reagent flows through the membrane. The detection of bound detection reagent may then be performed as described above. In the strip test format, one end of the membrane to which polypeptide is bound is immersed in a solution containing the sample. The sample migrates along the membrane through a region containing detection reagent and to the area of immobilized polypeptide. Concentration of detection reagent at the polypeptide indicates the presence of T. cruzi antibodies in the sample. Such tests can typically be performed with a very small amount (e.g., one drop) of patient serum or blood.

The assays discussed above may be performed using one or more of the polypeptides described herein. Alternatively, the sensitivity may be improved by using epitopes of one or more additional T. cruzi antigens in combination with the above polypeptide(s). In particular, epitopes of TcD (disclosed, for example, in U.S. Pat. No. 5,304,371), PEP-2 and/or TcE (both of which are disclosed, for example, in U.S. Ser. No. 08/403,379, filed Mar. 14, 1995) may be used in conjunction with the above polypeptide(s). The PEP-2 antigenic epitope is also discussed in Peralta et al., J Clin. Microbiol. 32:971-74, 1994. The sequence of TcD is provided in SEQ ID NO:50, the sequence of TcE is provided in SEQ ID NO:51. The TcD antigenic epitope preferably has the amino acid sequence Ala Glu Pro Lys Ser Ala Glu Pro Lys Pro Ala Glu Pro Lys Ser (SEQ ID NO:53) or the amino acid sequence Ala Glu Pro Lys Pro Ala Glu Pro Lys Ser Ala Glu Pro Lys Pro (SEQ ID NO:54). The TcE epitope preferably has the amino acid sequence Lys Ala Ala Ile Ala Pro Ala Lys Ala Ala Ala Ala Pro Ala Lys Ala Ala Thr Ala Pro Ala (SEQ ID NO:55) or the amino acid sequence Lys Ala Ala Ala Ala Pro Ala Lys Ala Ala Ala Ala Pro Ala Lys Ala Ala Ala Ala Pro Ala (SEQ ID NO:56), and the PEP2 epitope preferably has the amino acid sequence Gly Asp Lys Pro Ser Pro Phe Gly Gln Ala Ala Ala Gly Asp Lys Pro Ser Pro Phe Gly Gln Ala (SEQ ID NO:57).

Additional epitopes may be present within the same polypeptide (i.e., in a combination polypeptide) or may be included in separate polypeptides. Combination polypeptides may be prepared either synthetically, as described below in Example 2, or using recombinant DNA technology as detailed below in Example 7. Preferably, the polypeptides are immobilized by adsorption on a solid support such as a well of a microtiter plate or a membrane, as described above, such that a roughly similar amount of each polypeptide contacts the support, and such that the total amount of polypeptide in contact with the support ranges from about 1 ng to about 10 μg. The remainder of the steps may generally be performed as described above.

The polypeptides described above may also be used following diagnosis using one or more of the epitopes from TcD, TcE and/or PEP2. In this embodiment, the polypeptides of the present invention are used to confirm a diagnosis of T. cruzi infection based on a screen with TcD, TcE and/or PEP2. Diagnosis of T. cruzi infection using epitopes from TcD, TcE and/or PEP2 is described in U.S. Ser. No. 08/403,379, filed Mar. 14, 1995.

In yet another aspect of this invention, methods are provided for detecting T. cruzi in a biological sample using monospecific antibodies (which may be polyclonal or monoclonal) to one or more epitopes, as described above. Antibodies to purified or synthesized polypeptides may be prepared by any of a variety of techniques known to those of ordinary skill in the art. See, e.g., Harlow and Lane, Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, 1988. In one such technique, an immunogen comprising the antigenic polypeptide is initially injected into any of a wide variety of mammals (e.g., mice, rats, rabbits, sheep and goats). In this step, the polypeptides of this invention may serve as the immunogen without modification. Alternatively, particularly for relatively short polypeptides, a superior immune response may be elicited if the polypeptide is joined to a carrier protein, such as bovine serum albumin or keyhole limpet hemocyanin. The immunogen is injected into the animal host, preferably according to a predetermined schedule incorporating one or more booster immunizations, and the animals are bled periodically. Polyclonal antibodies specific for the polypeptide may then be purified from such antisera by, for example, affinity chromatography using the polypeptide coupled to a suitable solid support.

Monoclonal antibodies specific for the antigenic polypeptide of interest may be prepared,. for example, using the technique of Kohler and Milstein, Eur. J. Immunol. 6:511-519, 1976, and improvements thereto. Briefly, these methods involve the preparation of immortal cell lines capable of producing antibodies having the desired specificity (i.e., reactivity with the polypeptide of interest). Such cell lines may be produced, for example, from spleen cells obtained from an animal immunized as described above. The spleen cells are then immortalized by, for example, fusion with a myeloma cell fusion partner, preferably one that is syngeneic with the immunized animal. A variety of fusion techniques may be employed. For example, the spleen cells and myeloma cells may be combined with a nonionic detergent for a few minutes and then plated at low density on a selective medium that supports the growth of hybrid cells, but not myeloma cells. A preferred selection technique uses HAT (hypoxanthine, aminopterin, thymidine) selection. After a sufficient time, usually about 1 to 2 weeks, colonies of hybrids are observed. Single colonies are selected and tested for binding activity against the polypeptide. Hybridomas having high reactivity and specificity are preferred.

Monoclonal antibodies may be isolated from the supernatants of growing hybridoma colonies. In addition, various techniques may be employed to enhance the yield, such as injection of the hybridoma cell line into the peritoneal cavity of a suitable vertebrate host, such as a mouse. Monoclonal antibodies may then be harvested from the ascites fluid or the blood. Contaminants may be removed from the antibodies by conventional techniques, such as chromatography, gel filtration, precipitation, and extraction.

Monospecific antibodies to epitopes of one or more of the polypeptides described herein may be used to detect T. cruzi infection in a biological sample using any of a variety of immunoassays, which may be direct or competitive. Suitable biological samples for use in this aspect of the present invention are as described above. Briefly, in one direct assay format, a monospecific antibody may be immobilized on a solid support (as described above) and contacted with the sample to be tested. After removal of the unbound sample, a second monospecific antibody, which has been labeled with a reporter group, may be added and used to detect bound antigen. In an exemplary competitive assay, the sample may be combined with the monoclonal or polyclonal antibody, which has been labeled with a suitable reporter group. The mixture of sample and antibody may then be combined with polypeptide antigen immobilized on a suitable solid support. Antibody that has not bound to an antigen in the sample is allowed to bind to the immobilized antigen, and the remainder of the sample and antibody is removed. The level of antibody bound to the solid support is inversely related to the level of antigen in the sample. Thus, a lower level of antibody bound to the solid support indicates the presence of T. cruzi in the sample. To determine the presence or absence of T. cruzi infection, the signal detected from the reporter group that remains bound to the solid support is generally compared to a signal that corresponds to a predetermined cut-off value. Such cut-off values may generally be determined as described above. Any of the reporter groups discussed above in the context of ELISAs may be used to label the monospecific antibodies, and binding may be detected by any of a variety of techniques appropriate for the reporter group employed. Other formats for using monospecific antibodies to detect T. cruzi in a sample will be apparent to those of ordinary skill in the art, and the above formats is provided solely for exemplary purposes.

In another aspect of this invention, vaccines and pharmaceutical compositions are provided for the prevention of T. cruzi infection, and complications thereof, in a mammal. The pharmaceutical compositions generally comprise one or more polypeptides, containing one or more epitopes of T. cruzi proteins, and a physiologically acceptable carrier. The vaccines comprise one or more of the above polypeptides and an adjuvant, for enhancement of the immune response.

Routes and frequency of administration and polypeptide doses will vary from individual to individual and may parallel those currently being used in immunization against other protozoan infections. In general, the pharmaceutical compositions and vaccines may be administered by injection (e.g., intramuscular, intravenous or subcutaneous), intranasally (e.g., by aspiration) or orally. Between 1 and 4 doses may be administered for a 2-6 week period. Preferably, two doses are administered, with the second dose 2-4 weeks later than the first. A suitable dose is an amount of polypeptide that is effective to raise antibodies in a treated mammal that are sufficient to protect the mammal from T. cruzi infection for a period of time. In general, the amount of polypeptide present in a dose ranges from about 1 pg to about 100 mg per kg of host, typically from about 10 pg to about 1 mg, and preferably from about 100 pg to about 1 μg. Suitable dose sizes will vary with the size of the animal, but will typically range from about 0.01 mL to about 5 mL for 10-60 kg animal.

While any suitable carrier known to those of ordinary skill in the art may be employed in the pharmaceutical compositions of this invention, the type of carrier will vary depending on the mode of administration. For parenteral administration, such as subcutaneous injection, the carrier preferably comprises water, saline, alcohol, a fat, a wax or a buffer. For oral administration, any of the above carriers or a solid carrier, such as mannitol, lactose, starch, magnesium stearate, sodium saccharine, talcum, cellulose, glucose, sucrose, and magnesium carbonate, may be employed. Biodegradable microspheres (e.g., polylactic galactide) may also be employed as carriers for the pharmaceutical compositions of this invention.

Any of a variety of adjuvants may be employed in the vaccines of this invention to nonspecifically enhance the immune response. Most adjuvants contain a substance designed to protect the antigen from rapid catabolism, such as aluminum hydroxide or mineral oil, and a nonspecific stimulator of immune response, such as lipid A, Bordella pertussis or Mycobacterium tuberculosis. Such adjuvants are commercially available as, for example, Freund's Incomplete Adjuvant and Complete Adjuvant (Difco Laboratories, Detroit, Mich.) and Merck Adjuvant 65 (Merck and Company, Inc., Rahway, N.J.).

The following Examples are offered by way of illustration and not by way of limitation.

EXAMPLES Example 1 A. Preparation of DNA Encoding T. cruzi Antigens

This Example illustrates the preparation of genomic and cDNA olecules encoding T. cruzi Antigens.

Preparation of Genomic Clones

A genomic expression library was constructed from randomly sheared T. cruzi genomic DNA (Tulahuen C2 strain) using the Lambda ZAP expression system (Stratagene, La Jolla, Calif.) according to the manufacturer's instructions. In one screen, the library was screened with a pool of sera from five patients that displayed high reactivity with parasite lysate and/or one or both of the T. cruzi antigens TcD and TcE, described in U.S. Pat. No. 5,304,371 and U.S. Ser. No. 08/403,379, filed Mar. 14, 1995. Each of the five patients' sera was determined to be reactive based on Western and ELISA assays with whole lysate and/or TcD or TcE. Anti-E. coli reactivity was removed from the serum prior to screening by adsorption. 50,000 pfu of the unamplified library was screened with the serum pool and plaques expressing proteins that reacted with the serum were detected using protein A-horseradish peroxidase (with the ABTS substrate). A subsequent screen was then performed with a pool of sera from three patients lacking detectable anti-TcD antibody in Western and ELISA assays using recombinant TcD.

A similar screen was performed using a pool of sera that displayed low reactivity with lysate, TcD and TcE (i.e., detected a signal less than 3 standard deviations over background reactivity in an ELISA or Western assay), followed by a subsequent screen with patient sera lacking detectable anti-TcD antibody, as described above.

Twenty-eight clones that expressed proteins which reacted with both pools of sera in at least one of the above screens were then isolated. Excision of the pBSK(−) phagemid (Stratagene, Inc., La Jolla, Calif.) was carried out according to the manufacturer's protocol. Overlapping clones were generated by exonuclease III digestion and single-stranded templates were isolated after infection with VCSM 13 helper phage. The DNA was sequenced by the dideoxy chain termination method or by the Taq di-terminator system, using an Applied Biosystem automated sequencer, Model 373A.

Of the 28 clones, five had been reported previously, two were identical, and eight contained identical peptide sequences represented by a degenerate 42 base pair repeat. SEQ ID NO:16 shows the prototype clone containing the 42 base pair repeat sequence. Accordingly, 14 novel DNA sequences encoding T. cruzi antigens were prepared using the above screen with the reactive pool of sera (shown in SEQ ID NO:1-SEQ ID NO:16, where SEQ ID NO:4 and SEQ ID NO:5 represent the 5′ and 3′ ends, respectively, of a single clone, SEQ ID NO:9 and SEQ ID NO:10 represent the 5′ and 3′ ends, respectively, of a single clone. One novel sequence was obtained with the screen employing the sera with low reactivity (shown in SEQ ID NO:17 (5′ end) and SEQ ID NO:18 (3′ end)).

B. Preparation of cDNA Clones

Poly A+RNA was purified from the intracellular amastigote stage of T. cruzi (Tulahuen C2 strain). The RNA was reverse transcribed and used in the construction of a unidirectional cDNA expression library in the Lambda UniZap expression vector (Stratagene, La Jolla, Calif.) according to the manufacturer's instructions. 50,000 pfu of the unamplified library was screened with a serum pool containing patient sera that displayed both high and low serological reactivity, followed by a subsequent screen with patient sera lacking detectable anti-TcD antibody, as described above. A total of 32 clones were isolated from this screen. Twenty-five of these clones were proteins of the translational apparatus that have been previously identified as highly immunogenic, and all were different from the clones identified by screening the genomic expression library. The remaining seven are represented by the sequences provided in SEQ ID NO:19-SEQ ID NO:22. The sequence recited in SEQ ID NO:22 is that of T. cruzi ubiquitin.

Example 2 Synthesis of Synthetic Polyeptides

This Example illustrates the synthesis of polypeptides having sequences derived from T. cruzi antigens described herein.

Polypeptides may be synthesized on a Millipore 9050 peptide synthesizer using FMOC chemistry with HBTU (O-benzotriazole-N,N,N′, N′-tetramethyuronium hexafluorophosphate) activation. A gly-cys-gly sequence may be attached to the amino or carboxyl terminus of the peptide to provide a method of conjugation or labeling of the peptide. Cleavage of the peptides from the solid support may be carried out using the following cleavage mixture: trifluoroacetic acid:ethanediol:thioanisole:water:phenol (40:1:2:2:3). After cleaving for 2 hours, the peptides may be precipitated in cold methyl-t-butyl-ether. The peptide pellets may then be dissolved in water containing 0.1% trifluoroacetic acid (TFA) and lyophilized prior to purification by C18 reverse phase HPLC. A gradient of 0%-60% acetonitrile (containing 0.1% TFA) in water (containing 0.1%TFA) may be used to elute the peptides. Following lyophilization of the pure fractions, the peptides are characterized using electrospray mass spectrometry and by amino acid analysis.

This procedure was used to synthesize peptides such as Tcc22-1, Tcc22-1+, Tcc22-2.1 (contained within SEQ ID NO:41), TcLo1.1,1.2 and 1.3 (contained within SEQ ID NO:34, 35 and 36) and TcHi10.1 and 10.3 (SEQ ID NO:26 and 27) which have the following sequences:

Tcc22-1                                    VRASNCRKKACGHCSNLRMKKK Tcc22-1+               EALAKKYNWEKKVCRRCYARLPVRASNCRKKACGHCSNLRMKKK Tcc22-2.1 VLRLRGGVMEPTLEALAKKYNWEKKVCRRCYARL TcLo1.1 GYVRGRKQRWQLHACGYVRGRKQRRQLHACGYVRGRKQRWQLHAF TcLo1.2 GTSEEGSRGGSSMPSGTSEEGSRGGSSMPA TcLol.3 VRPRKEAEVAAPCLRVRPRKEAEEAAPCLR TcHi10.1 SVPGKRLRNSHGKSLRNVHGKRPKNEHGKRLRSVPNERLR TcHi10.3 EAEELARQESEERARQEAEERAWQEAEERAQREAEERAQR

Example 3 Serological Reactivity of T. cruzi Recombinant Antigens

This example illustrates the diagnostic properties of several recombinant antigens found to be serologically active. This includes studies of reactivity with T. cruzi positive and negative sera as well as cross reactivity studies with sera from patients with other diseases.

Assays were performed in 96 well plates (Coming Easiwash, Coming, N.Y.). Wells were coated in 50 μl of carbonate coating buffer pH 9.6. For T. cruzi lysate, 100 ng/well was used, and for each of the recombinant antigens 200 ng/well was used. The wells were coated overnight at 4° C. (or 2 hours at 37° C.). The plate contents were then removed and wells were blocked for 2 hours with 200 μl of PBS/1%BSA. After the blocking step, the wells were washed five times with PBS/0.1% Tween 20™. 50 μl of sera (either positive or negative for T. cruzi infection), diluted 1:50 in PBS/0.1% Tween 20/0.1%BSA was then added to each well and incubated for 30 minutes at room temperature. The plates were then washed again five times with PBS/0.1% Tween 20™.

The enzyme conjugate (horse radish peroxidase-Protein A, Zymed, San Francisco, Calif.) was then diluted 1:20,000 in PBS/0.1% Tween 20™/0.1%BSA, and 50 μl of the diluted conjugate was added to each well and incubated for 30 minutes at room temperature. Following incubation the wells were again washed five times with PBS/0.1% Tween 20™. 100 μl of the peroxidase substrate, tetramethylbenzidine (Kirkegaard and Perry Laboratories, Gaithersburg, Md.) was added, undiluted, to each of the wells and incubated for 15 minutes. The reaction was stopped by the addition of 100 μl of 1N H₂SO₄to each well, and the plates were read at 450 nm.

FIG. 1 shows the reactivity of the recombinant rTcc6 (SEQ ID NO:39) as compared to that of T. cruzi lysate. Based on a cutoff of the mean of the negatives plus 3 standard deviations, 49 out of 50 serum samples were positive with lysate, and 34 out of 50 were positive with rTcc6. In a similar study (shown in FIG. 2), the recombinant rTcc22 (SEQ ID NO:41) was found to have a sensitivity of 79.2% (38 out of 48 serum samples were positive). Comparative studies of the recombinant rTcc38 (SEQ ID NO:38) with T. cruzi lysate using similar criteria showed that 24/39 were positive compared with 39/39 for lysate (FIG. 3). Tcc38 when tested with potentially cross reacting sera showed improved specificity over T. cruzi lysate.

The recombinant TcHi12 (SEQ ID NO:37) was also found to be immunoreactive (FIG. 2) having a sensitivity of 62.5% (15/24).

Example 4 Serological Reactivity of T. cruzi Synthetic Peptide Antigens

This example illustrates the diagnostic properties of several of the peptides described in Example 2. These peptides were tested for reactivity with T. cruzi positive and negative sera and, in some cases, for cross reactivity with sera from patients with other, potentially cross reactive, diseases.

The first group of peptides included different reading frames to determine the most reactive repeat sequence. The peptides tested were TcLo1.1 (contained within SEQ ID NO:34), TcLo1.2 (contained within SEQ ID NO:35) and TcLo1.3 (contained within SEQ ID NO:36), representing reading frames 1, 2 and 3 of the DNA sequence provided in SEQ ID NO:18, and TcHi10.1 (SEQ ID NO:26) and TcHi10.3 (SEQ ID NO:27) which represent two of the reading frames for the TcHi10 sequence (shown in SEQ ID NO:5). The data is shown in FIG. 4. In the case of the TcLo frames, both the TcLo1.1 and 1.2 peptides were strongly reactive but the TcLo1.2 was superior in signal to noise when tested on sera from T. cruzi positive and negative individuals. TcLo1.3 had lower signal but also low background. In this study lysate detected 24/24 positives, TcLo1.1 detected 21/24, TcLo1.2 detected 23/24 and TcLo1.3 detected 15/24. In the same study, the two frames TcHi10.1 and 10.3 detected 19/24 and 14/24 positives respectively, but with lower signal than for TcLo1. Cross reactivity studies with these different reading frames demonstrate that TcLo1.2 has minimal cross reactivity with the sera tested (FIG. 5) as compared to T. cruzi lysate.

As discussed in Example 2, overlapping peptides were also synthesized for rTcc22 to determine the active epitope. The peptides Tcc22-1, 1+ and 2 were tested with T. cruzi positive and negative sera. The results are shown in FIG. 2. The Tcc22-1+ and Tcc22-2.1 peptides were more reactive than the Tcc22-1 peptide. In the first experiment, Tcc22-1 and Tcc22-1+ detected 29/48 and 36/48 positives as compared to the recombinant Tcc22 which detected 38/48 positives. In a subsequent experiment, Tcc22-2.1 was also shown to be reactive but with less signal than Tcc22-1+ at the same plate coating level.

A polypeptide having the TcH15 frame 3 repeat sequence (SEQ ID NO:49) was also synthesized and tested in an ELISA assay using a coating level of 200 ng/well. A total of 48 T. cruzi positive sera and 26 negative sera were tested in order to determine the reactivity of this peptide sequence. In this study, the peptide had a sensitivity of 68.75% (detecting 33 out of 48 positives) and a specificity of 92.3% (24 out of 36 negatives), indicating that this polypeptide has potential significance in detecting T. cruzi infections. The results of this assay are presented in Table 1, below.

TABLE 1 Reactivity of TcHi15 Frame 3 Polypeptide with T. cruzi- Positive and Negative Sera T. cruzi T. cruzi Sample ID Status OD 450 Sample ID Status OD 450 Tc011095-1 Positive 0.696 DL4-0106 Negative 0.167 Tc011095-2 Positive 0.699 DL4-0112 Negative 0.05 Tc011095-3 Positive 1.991 DL4-0127 Negative 0.240 Tc011095-4 Positive 3 DL4-0140 Negative 0.008 Tc011095-5 Positive 0.098 DL4-0145 Negative 0.107 Tc011095-6 Positive 0.238 DL4-0161 Negative 0.119 Tc011095-7 Positive 0.115 DL4-0162 Negative 1.187 Tc011095-8 Positive 0.156 DL4-0166 Negative 0.210 Tc011095-9 Positive 0.757 DL4-0167 Negative 0.131 Tc011095-10 Positive 1.147 DL4-0172 Negative 0.073 Tc011095-11 Positive 0.264 DL4-0175 Negative 0.117 Tc011095-12 Positive 1.7 DL4-0176 Negative 0.815 Tc011095-13 Positive 1.293 AT4-0013 Negative 0.100 Tc011095-14 Positive 0.242 AT4-0041 Negative 0.107 Tc011095-15 Positive 0.636 AT4-0062 Negative 0.28 Tc011095-16 Positive 0.44 AT4-0063 Negative 0.155 Tc011095-17 Positive 3 E4-0051 Negative 0.162 Tc011095-18 Positive 1.651 E4-0059 Negative 0.176 Tc011095-19 Positive 0.19 E4-0068 Negative 0.241 Tc011095-20 Positive 0.916 E4-0071 Negative 0.127 Tc011095-21 Positive 0.715 C4-0072 Negative 0.101 Tc011095-22 Positive 1.336 C4-0088 Negative 0.141 Tc011095-23 Positive 1.037 C4-0090 Negative 0.078 Tc011095-24 Positive 0.332 C4-0096 Negative 0.162 Tc011095-25 Positive 0.413 C4-0101 Negative 0.181 Tc011095-26 Positive 0.266 C4-0105 Negative 0.702 Tc011095-27 Positive 1.808 Tc011095-28 Positive 0.238 Tc011095-29 Positive 0.266 Tc011095-30 Positive 1.563 Tc011095-31 Positive 0.352 Sensitivity 33/48 68.75% Tc011095-32 Positive 0.208 Specificity 24/26 92.30% Tc011095-33 Positive 0.656 Mean Pos. 0.9188 Tc011095-34 Positive 1.281 Std Dev Pos. 0.79 Tc011095-35 Positive 0.907 Mean Neg. 0.1508 Tc011095-36 Positive 0.429 Std Dev Neg. 0.06695 Tc011095-37 Positive 0.454 Tc011095-38 Positive 0.725 Tc011095-39 Positive 0.703 Tc0394-7 Positive 0.186 Tc0394-8 Positive 1.06 Tc0394-9 Positive 1.813 Tc0394-10 Positive 0.131 Tc0394-11 Positivc 1.631 Tc0394-12 Positive 0.613 Tc0394-13 Positive 3 Tc0394-14 Positive 0.268 Tc0394-15 Positive 2.211

Example 5 Serological Reactivity of Peptide Combinations

This example illustrates the diagnostic properties of several peptide combinations.

The TcLo1.2 peptide (contained within SEQ ID NO:35) was tested in combination with the synthetic peptide TcD and also the dual epitope peptides D/2 (which contains the TcD and the PEP-2 sequences) and D/E (which contains TcD and TcE sequences). These combinations were compared with the individual peptides as well as the tripeptide 2/D/E, which contains TcD, TcE and PEP-2. The TcD sequence used was Ala Glu Pro Lys Ser Ala Glu Pro Lys Pro Ala Glu Pro Lys Ser (SEQ ID NO:53), the TcE sequence was Lys Ala Ala Ile Ala Pro Ala Lys Ala Ala Ala Ala Pro Ala Lys Ala Ala Thr Ala Pro Ala (SEQ ID NO:55), and the PEP2 sequence was Gly Asp Lys Pro Ser Pro Phe Gly Gln Ala Ala Ala Gly Asp Lys Pro Ser Pro Phe Gly Gln Ala (SEQ ID NO:57).

The data are shown in FIG. 6. The results show that TcLo1.2 can augment the reactivity of TcD, D/2 and D/E, as summarized in Table 2.

TABLE 2 Sensitivity of Peptide Combinations in the Detection of T. cruzi Infection Peptides Number of Positives TcD 62/67 TcE 50/67 PEP-2 66/67 TcLo1.2 61/67 TcD + TcLo1.2 66/67 D/2 + TcLo1.2 67/67 D/E + TcLo1.2 67/67 2/D/E 67/67

These results demonstrate the use of T. cruzi antigens as described herein to enhance the serodiagnostic properties of other antigens.

Example 6 Serological Reactivity of TcE Repeat Sequences

This example illustrates the diagnostic properties of several TcE repeat sequences.

The repeat sequence region of the recombinant TcE contains several degeneracies, resulting in residues where an A (alanine), T (threonine) or I (isoleucine) can be present in the repeat sequence. In order to represent all degeneracies, the original sequence for the synthetic TcE peptide was made with an A, T and I in a single peptide containing three repeats (see Example 5). In order to further epitope map the repeat region and to determine the number of repeats required for serological activity, the following peptides were prepared as described in Example 2:

original TcE KAAIAPAKAAAAPAKAATAPA (SEQ ID NO: 55) TcE(3A) KAAAAPAKAAAAPAKAAAAPA (SEQ ID NO: 58) TcE(3T) KAATAPAKAATAPAKAATAPA (SEQ ID NO: 59) TcE(3I) KAAIAPAKAAIAPAKAAIAPA (SEQ ID NO: 60) TcE(2A) KAAAAPAKAAAAPA (SEQ ID NO:61) TcE(AT) KAAAAPAKAATAPA (SEQ ID NO:62)

The serological reactivity of these peptides was then compared. A total of 24 positive and 21 negative sera were tested with each of the TcE variants as the solid phase in an ELISA assay performed as described in Example 3, using 25 ng/well of peptide. The reactivity of the different peptides is shown in FIG. 7. The highest reactivity was seen with the 3-repeat peptide in which each repeat contained an A at the degenerate residue (TcE(3A)). This peptide displayed even higher reactivity than the original TcE sequence containing an A, T and I residue in the three repeats. The 31 and 3T variants by contrast were essentially negative with the T. cruzi positive samples tested. The sequence containing two repeats with A (TcE(2A)) was clearly less reactive than the 3A sequence and the two repeat sequence with an A and a T (TcE(AT)) was negative. Based on a cutoff of the mean of the negatives plus three standard deviations, the original TcE (A,T,I) detected 17 out of 24 positives and the 3A variant detected 19 out of 24 positives. It also appears that to obtain maximal serological activity at least three repeats are required.

Example 7 Serological Reactivity of Multi-epitope Peptide Combinations

This example illustrates the diagnostic properties of several multi-epitope peptide combinations.

Two dipeptides PEP-2/TcLo1.2, which contains the PEP-2 (SEQ ID NO:57) and TcLo1.2 (SEQ ID NO:35) sequences, and TcD/TcE, which contains the TcD (SEQ ID NO:53) and TcE (SEQ ID NO:55) sequences, were synthesized as described above in Example 2. The reactivity of these two dipeptides with T. cruzi antibody-positive sera was compared to that of the tripeptide 2/D/E. ELISA's were performed as described in Example 3 using PEP-2/TcLo1.2 at 250 ng/well and TcD/TcE at 50 ng/well. The results of this study are shown in FIG. 8. One T. cruzi positive serum found not to react with the tripeptide 2/D/E was used in screening for the TcLo1.2 epitope. This serum was detected by the TcLo1.2 epitope and also by the dipeptide mix (PEP-2/TcLo1.2 together with TcD/TcE) as expected.

A tetrapeptide containing the four immunoreactive T. cruzi epitopes PEP-2, TcD, TcE and TcLo1.2 in a linear sequence, herein after referred to as 2/Lo/2E/D (SEQ ID NO:63) was synthesized as described in Example 2. This tetrapeptide was coated at 100 ng/well and its reactivity with T. cruzi positive and negative sera was assayed as described in Example 3. The reactivity of the tetrapeptide 2/Lo/2E/D is shown in FIG. 8. The one T. cruzi positive serum found not to react with the tripeptide 2/D/E was detected by the tetrapeptide as expected.

The four immunoreactive T. cruzi epitopes PEP-2, TcD, TcE and TcLo1.2 may also be linked into one reagent by the use of a ‘branched’ peptide originating from a lysine core residue. Orthogonal protection of the lysine, for example employing 9-Fluorenylmethoxycarbonyl (Fmoc) on the α-amino group and 1-(4,4-Dimethyl-2,6-dioxocyclohex-1-ylidene)ethyl (Dde) on the ε-amino group, is used to permit selective deprotection of one amino group in the presence of the other, thereby allowing the synthesis of the first peptide chain from either the α- or ε-group on the lysine. This first peptide chain is terminated with a protecting group that is not removed during the course of the synthesis of the second peptide chain. For example, a tert-Butoxy carbonyl (Boc) amino acid could be used with the Dde and Fmoc combination. The remaining lysine amino protecting group is then removed before a second amino acid chain is synthesized from the second amino moiety. For example, ε-Dde is removed with 20% hydrazine. Cleavage of the branched peptide from a solid support and removal of the N-α-Boc moiety is carried out using trifluoroacetic acid, following standard protocols. Using this approach two independent amino acid sequences can be built from a ‘core’ lysine residue, as shown below, thus allowing various combinations of TcD, TcE, PEP2, TcLo1.2, and other epitopes to be coupled to the core residue. Purification of the resulting peptide is performed as described in Example 2.

Example 8 Preparation of Multi-epitope Peptide Combinations using Recombinant DNA Technology

This example illustrates the preparation of a fusion polypeptide (hereinafter referred to as TcF) of the peptides PEP-2 (SEQ ID NO:57), TcD (SEQ ID NO:53), TcE (SEQ ID NO:55) and TcLo1.2 (SEQ ID NO:35) using recombinant DNA technology.

The TcF polypeptide fusion was created by synthesizing overlapping phosphorylated oligonucleotides, annealing the matched oligonucleotide pairs to create double stranded DNA, ligating the annealed pairs with vector DNA that was cut with appropriate enzymes, and transforming into suitable bacteria host strains (XL2, Stratagene, La Jolla, Calif.) for sequencing. Once the correct sequence was obtained, the construct was subcloned into a modified pET28 vector and transformed into BLR pLYS S (Novagen, Madison, Wis.) for expression and purification.

For construction of the PEP2-TcD fusion, the matched pairs of oligonucleotides PDM-95 (SEQ ID NO:66) and PDM-98 (SEQ ID NO:67); PDM-96 (SEQ ID NO:68) and PDM-99 (SEQ ID NO:69); and PDM-97 (SEQ ID NO:70) and PDM-100 (SEQ ID NO:71) were synthesized, kinased and annealed. These three pairs of annealed oligos were then ligated, digested with EcoRI (New England Biolabs, Beverly, Mass.) and cloned into a modified T vector construct with Eco72I and EcoRI. For construction of the PEP2-TcD-TcE fusion, the following matched pairs of oligonucleotides were synthesized, kinased and annealed: PDM-103 (SEQ ID NO:72) and PDM-105 (SEQ ID NO:73); and PDM-104 (SEQ ID NO:74) and PDM-106 (SEQ ID NO:75). These two pairs of annealed oligos were ligated into the pT7ΔL2PEP2-TcD construct cut with Eco47III (New England Biolabs) and EcoRI.

For construction of the PEP2-TcD-TcE-Lo1.2 fusion, the two matched pairs of oligonucleotides PDM-108 (SEQ ID NO:76) and PDM-110 (SEQ ID NO:77); and PDM-109 (SEQ ID NO:78) and PDM-111 (SEQ ID NO:79) were synthesized, kinased and annealed. These two pairs of annealed oligonucleotides were ligated with the pT7ΔL2PEP2-TcD-TcE construct which had been cut with EagI, treated for blunt ends with T4 DNA polymerase and then cut with EcoRI. Due to an internal EagI site in the pT7ΔL2 vector, a PCR reaction was performed with the ligation mix as template in order to clone the full length PEP2-TcD-TcE-Lo1.2 construct. PCR was accomplished with the primers PDM-101 and PDM-107 (SEQ ID NOS:80 and 81, respectively) using the following conditions:

96° C. 2 minutes

96° C. 15 seconds 61° C. 15 seconds, 72° C. 1 minute×40 cycles

72° C. 4 minutes.

Pful DNA polymerase (Stratagene, La Jolla, Calif.) was used for the PCR reaction. Following PCR, the DNA was subjected to an ethanol precipitation, digested with SmaI and EcoRI, and ligated into a modified T vector construct which had been digested with Eco72I and EcoRI.

The resulting clone was digested with Hind III (Gibco BRL, Gaitherburg, Md.) and Sph I (New England Biolabs), treated with T4 DNA polymerase for blunt ends and then religated in order to delete the vector's internal Eag I and Nsi I sites. This new clone was then digested with Eag I and Nsi I, treated with T4 DNA polymerase for blund ends, and religated in order to create a stop codon in frame at the end of the TcLo1.2 sequence. This clone was digested with NdeI and Eco RI, and subcloned into a modified pET28b vector cut with the same enzymes.

The resulting expression construct was transformed into BLR pLys S E. coli (Novagen) and grown overnight in LB broth with kanamycin (30 ug/ml, Sigma, St. Louis, Mo.) and chloramphenicol (34 ug/ml Sigma). The overnight culture (12 ml) was used to inoculate 500 ml of 2XYT with the same antibiotics and the culture was induced at an OD560 of 0.3-0.6 with IPTG to a final concentration of 1.0 mM. Four hours post-induction, the bacteria were harvested and sonicated in 20 mM Tris (8.0), 100 mM NaCl, 0.1% DOC, 20 ug/ml Leupeptin and 20 mM PMSF followed by centrifugation at 26,000×g. The fusion protein was found in the soluble supernatant after sonication. The supernantant was bound to a Pro-bond nickel resin column (Invitrogen, Carlsbad, Calif.). The column was washed with 50 ml of 20 mM Tris (8.0), 100 mM NaCl wash buffer and eluted with an increasing imidazole concentration. Specifically, the elutions were made with 50 mM, 100 mM and 500 mM imidazole in the 20 mM Tris (8.0), 100 mM NaCl wash buffer. The eluates containing the protein of interest were pooled and dialyzed against 10 mM Tris (8.0).

After dialysis, the protein was concentrated, sterile filtered and tested for endotoxins. Test results indicated a high level of endotoxin contamination. The sterile filtered protein was therefore purified over a High Q anion exchange column (Biorad, Hercules, Calif.), binding in 10 mM Tris (8.0) and eluting with a NaCl gradient up to 1 M in 10 mM Tris (8.0). The elutions containing the protein of interest were pooled and dialyzed against 10 mM Tris (8.0). After dialysis, the protein was reconcentrated, sterile filtered and a BCA assay (Pierce, Rockford, Ill.) was performed to determine protein concentration. The determined amino acid sequence of TcF is provided in SEQ ID NO:82.

The reactivity of the recombinant fusion polypeptide TcF with sera from T. cruzi patients and from normal donors was examined by ELISA as described above. As shown in FIG. 11, the reactivity of TcF was found to be very similar to that of the branched synthetic tetrapeptide 2/D/E/Lo1.2.

It is envisioned that the order of the peptides in the recombinant fusion polypeptide TcF could be altered without significantly changing the activity of the polypeptide. Also, the inclusion of a Gly-Cys-Gly linkage between the peptides may enhance solid phase binding without significantly affecting the activity of the polypeptide.

A fusion polypeptide (hereinafter referred to as TcF-2) of the peptides PEP-2 (SEQ ID NO:57), TcD (SEQ ID NO:53), TcE (SEQ ID NO:55) and TcLo1.2 (SEQ ID NO:35) with a glycine-cysteine-glycine amino acid spacer between each of the fused peptides was prepared by synthesizing overlapping phosphorylated oligos, annealing the matched oligo pairs to create double-stranded DNA, ligating the annealed pairs with vector DNA that was cut with appropriate enzymes and transformed into suitable bacterial host strains for sequencing (XL2, Stratagene). Once the correct sequence was obtained, the construct was subcloned into a modified pET28 vector and transformed into BLR pLYS S (Novagen, Madison, Wis.) for expression and purification.

More specifically, the PEP2-GCG-TcD fusion was constructed by synthesizing, kinasing and annealing the following matched pairs of oligos: PDM-95 (SEQ ID NO:66) and PDM-98 (SEQ ID NO:67); PDM-112 (SEQ ID NO:83) and PDM-113 (SEQ ID NO:84); and PDM-114 (SEQ ID NO:85) and PDM-115 (SEQ ID NO:86). The three pairs of annealed oligos were ligated, digested with EcoRI (New England Biolabs, Beverly, Mass.) and cloned into a modified pT7 blue construct with a His tag in frame when cut with Eco 72I and EcoRI. For construction of the PEP2-GCG-TcD-GCG-TcE fusion, the following matched pairs of oligos were synthesized, kinased and annealed: PDM-116 (SEQ ID NO:87) and PDM-117 (SEQ ID NO:88); and PDM-118 (SEQ ID NO:89) and PDM-119 (SEQ ID NO:90). These two pairs of matched oligos were then ligated into the above PEP2-GCG-TcD construct cut with Eco 47III (New England Labs.) and Eco RI.

The matched pairs of oligos PDM-120 (SEQ ID NO:92) and PDM-121 (SEQ ID NO:92), and PDM-122 (SEQ ID NO:93) and PDM-123 (SEQ ID NO:94) were synthesized, kinased and annealed, and then ligated with the above PEP2-GCG-TcD-GCG-TcE construct which had been cut with Eag I, treated for blunt ends with T4 DNA polymerase and then cut with Eco RI. This clone was then digested with Nde I (Gibco BRL) and Eco RI, and subcloned into a modified pET28 vector cut with the same enzymes.

The expression construct was then transformed to BLR pLys S E. coli (Novagen) and grown overnight in LB broth with kanamycin (30 ug/ml, Sigma, St. Louis, Mo.) and chloramphenicol (34 ug/ml, Sigma). 12 ml of the overnight culture was used to inoculate 500 ml of 2XYT with the same antibiotics and the culture was induced at an OD560 of 0.37 with IPTG to a final concentration of 1.0 mM. Four hours post-induction, the bacteria were harvested and sonicated in 20 mM Tris (8.0), 100 mM NaCl, 0.1% DOC, 20 ug.ml leupeptin, 20 mM PMSF followed by centrifugation at 26,000×g. The fusion protein was found in the soluble supernatant after sonication. The supernatant was then bound to Pro-bond nickel resin (Invitrogen, Carlsbad, Calif.). The column was washed with 50 ml of 20 mM Tris (8.0), 100 mM NaCl wash buffer and then eluted with an increasing imidazole concentration. The elutions were made with 50 mM, 100 mM and 500 mM imidazole in the 20 mM Tris (8.0), 100 mM NaCl wash buffer. The eluates containing the protein of interest were pooled and then dialyzed against 10 mM Tris (8.0).

After dialysis, the protein was taken over a High Q (Biorad, Hercules, Calif.) anion exchange column, binding in 10 mM Tris (8.0) and eluting with a NaCl gradient up to 1 M in 10 mM Tris (8.0). The elutions containing the protein of interest were pooled and dialyzed against 10 mM Tris (8.0). After dialysis, the protein was reconcentrated and sterile filtered, and a BCA assay (Pierce) was performed to determine protein concentration. The determined amino acid sequence for TcF-2 is provided in SEQ ID NO:95).

Example 9 Comparison of the Serological Reactivity of TcHi29 and TcE

The antigen TcHi29 (SEQ ID NO:52) was shown to be a polymorph of the TcE repeat sequence. A TcHi29 peptide was synthesized that had the following sequence as compared to TcE.

TcE KAAIAPAKAAAAPAKAATAPA (SEQ ID NO: 55) TcHi29 KTAAPPAKTAAPPAKTAAPPA (SEQ ID NO: 64)

FIG. 9 shows a comparison of the reactivity of these two related seqences with sera from T. cruzi positive patients as well as from other disease categories, as determined by ELISA using the procedure described above. The data indicate little or no cross reactivity with the other disease groups tested but the distribution of reactivity amongst the T. cruzi positive sera partially overlapped for the two peptides. Of the 53 consensus positive samples tested, TcE detected 31/53 and TcHi 29 36/53. Within this group TcE and TcHi29 both detected 24 of the same sera. TcE detected 7 positive sera not detected by TcHi29, which in turn detected 12 positive sera missed by TcE. A dipeptide, TcD/TcHi29, was also synthesized and used in combination with the PEP-2/TcLo1.2 dipeptide in ELISA (100 ng/well TcD/TcHi29, 250 ng/well PEP-2/TcLo1.2) and compared with the TcD/TcE plus PEP-2/TcLo1.2 dipeptide combination. As shown in FIG. 10, the data indicates that the overall activity of the two mixes are similar for both the T. cruzi positive and negative populations studied and suggests that, in such peptide combinations, TcHi29 can be considered to be an alternative to TcE.

From the foregoing, it will be appreciated that, although specific embodiments of the invention have been described herein for the purpose of illustration, various modifications may be made without deviating from the spirit and scope of the invention.

95 1 518 DNA Trypanosoma cruzi 1 cgggaaaaga aggctgttac gacgcacgag cttggctttg agggcgagga ctgggactac 60 gtgctggagc ggcggcgcgc ggaggtgaag gacgtgctgg ccgtcgagac ggcgcgggcg 120 ttgggactcg agcgtgagga cgtgctggag gtggaggtcg acgcagtgcc tcggagcctc 180 attgcgtttg tcacggtccg tcatccatca ctgctgagcg accgcaggtg gaagagacgc 240 tggcgcgctg cgagtacagg aaattgtggg cgctgtacga gacgcggcca ctggagtcgt 300 cagtgctgat gaggcggttt gagggcgacg actgggacct cgtggttgac aacaaccgca 360 ggaagcttga ggacgcgttc agcagggaga cggccgcgca ctgggcgtgt cgccgaggca 420 ggttgtgctt ctggactgca gggttggcag ccttctcatg gtattcaagg tgcttggatg 480 cgccatgagc gacgcagaga tcacggaacg gaccgagg 518 2 560 DNA Trypanosoma cruzi 2 cggcggtagt ctgcgatgct gtggaccgac gcattgaaat acacaccgtc ttcggcgttc 60 ctttttttta tatgtttttt tttattgaga agatgtcttg tttgttgttg ttttttttca 120 gtttttatga tacgagcagt ttgtccgact gcattcatgc agtgattggt aattctttct 180 attctttgga attatggcga tattattctt gtcttttaaa attcttacaa ccaattgtgc 240 cttagagttt cctgcttagt tgctattaac acactgttag gaacgcgaaa ccatgcagat 300 cttcgtgaag acactgacgg gcaagacgat cgcgctcgag gtggagtcca gcgacaccat 360 tgagaacgtg aaggcgaaga tccaggacaa ggagggtatc cgccggacca gcagcgcctg 420 atcttcgctg gcaagcagct ggaggacggc cgcacgctcg cagactacaa catccagaag 480 gagtccacgc tgcaccttgt gctgcgcctg cgcggcggca tgcagatctt cgtgaagaca 540 ctgacgggta aagacgatcg 560 3 436 DNA Trypanosoma cruzi Where n is an unknown nucleic acid 3 cggctgcctc ctctgcttcc ttcctcggac gtgcccgaag gcatggagct gcctcctctg 60 cttccttcct cggacatacc cgaaggcatg gagctgccac ctctgcttcc ttcctcggac 120 gtacccgcgg gcatggagct gacacctctg cttccttcct cggacgtgcc cgaaggcatg 180 gagctgccac ctctgcttcc ttcctcggac gtacccgcgg gcatggagct gccacctctg 240 sttccttcct cggacgtacc cgcgggcatg gagctgcctc ctctgcttcc ttcctcggac 300 gtacccgcgg rcatagagct gccacctctg atttcctncc tcggacgtac ccncaggnat 360 ggagatgnct cctctgnttc ctgcctcgga cgtncccnaa ggnatagagn tgcncctctg 420 nttcctncct cggaag 436 4 373 DNA Trypanosoma cruzi 4 cctcaggggc tcttggcgtt cctttttttc ttgttgtttt gagttttttt ttcttttgtt 60 ttggtttgtc gtctctgttt ttatgtgcgt tgttttcggt ttttcttttt gttcttcctg 120 cctgtcatgt gactagtttt atgttttcca ggccgaccgt cactcaattt ttttattttt 180 atttttattt atttatttga cccgcctttc tctgtagttt acgagagttt agatttttat 240 tgattggtag tttagggcca tcaggcggga ggggcgagtc tggcggaaga caaaacaaaa 300 tacgatggac tcgaccaaca gcatcgagaa atcgcttctg atggagatgg agcgggaggt 360 tgagagggcg agg 373 5 560 DNA Trypanosoma cruzi 5 cagaaaaaga acgtagattt ccaaccaaaa cagcaagagc ggatccaaca acgaccaaac 60 aactcattat tcgagctctc caaaatatat cgcttgcctt cgggattgaa ccctcatcta 120 cagtaaaata cgccgaaagc acgcaagaag aaaatggaaa acgttcacaa agtgaggccg 180 aggagcgtgc acggcgggag gctgaggaac gagcacggcg agaggctgag gaacgagccc 240 aacgagaggc tgaggaacga gcccaacgag aggctgagga acgagcacgg cgggaggctg 300 agaagcgtgc ccggcgagag gctaaggaac gagcatggca agaggccgaa gaacgagccc 360 aacgagaggc tgaggagcgt gcccggcgag aggctgagga gcgtgcccgg cgagaggttg 420 aggagcgtgc ccggcaagag gctgaggaac tcgcacggca agagtctgag gaacgtgcac 480 ggcaagaggc cgaagaacga gcatggcaag aggctgagga gcgtgcccaa cgagaggctg 540 aggagcgtgc tcaacgagcg 560 6 440 DNA Trypanosoma cruzi Where n is an unknown nucleic acid 6 gcctcctgca actcgagctg gcagcgtgga ggtgcngcag gaactctcaa nagangacgg 60 ctctccctcg atancnttcg gagtgacttn gactgttgcg ccntttccgt ntcactattt 120 ctattgcttt taatttgctg gagaggcgcg tgtaggaggg aaagagtagt aacatggcag 180 aatcatcaaa aacgatgttg cgttagtaga gaggagggaa acatcgagac gttgagggtt 240 gcgacggnca aaattatgta catttacctg aattaggata agacttcata tggcataaac 300 tcgtggcgtt gttggtggtt ataacaagca acggtgacga tgtcttaggc tacactgctg 360 cactcaaaga gttttacagg tacttgcggg atatttgttc ctgtgagttt gttttctatt 420 gtaatttatt nngtctcaat 440 7 1915 DNA Trypanosoma cruzi 7 cgatgcgtct gtcgtagacc tgggaggcga ggcccatggg acacactatg cctttttgcc 60 cgatgtgatc aaggggattg cgcaggaaga gctgtacctg gaagacgatg cgtacttcca 120 ggagttgctt gcgaggtata aagaacttgt ccctgtgggt gccgagccaa ccgagccacg 180 cgcaaagcag ttgcgcgagc aaatgcggat acgggctggg cagcttgctg ttgacacccg 240 aaagcttcat gcggccgaag agcgggctgc atcgcggatg gcgacacttt acccgtttgt 300 gggctcggcg ccgctgggag ttgctctgtg gaatatcccc gtggaggcgg acgaagagtt 360 ctgtgcactt ctgctgaagc gcgaagaagc gctggcgggg aagtcagggt ccgtccacga 420 agtggaatct gcgctgagcg cgcgtgcgga agcgatggcg aaggcggtgc tggaggagga 480 ggaggcgctt gcggcggcat ttccatttct ggggcggagt gttaagggag cccctctgcg 540 tgagttggct ctcatgtctg atcccaattt tgcggagctg gcgacacggc acgcgcagga 600 ggcgacctcg ggcgatgcgg cgggtatttt gcgccttgag caggagctgc gtgaccaggc 660 atgtcgcata gcacgtgagg tgcgagtggc tcggcggctt gacgccgtcg caatgaggac 720 ctgcacgagc ggtacccgtt tcttcccgag gagccggtgc gcggcattct tcttggtgct 780 gtgcgtccgg tgcagcaacc ggcgttccgc gagctttcaa acaagttgga tgagcagcgc 840 cgggacccga cacgcaacgc agccgcgatc cgcacgacgg aggagcagat gactgcgttg 900 gtggtgcgac tggctgagga gcgcgcggag gcgacggaga gggcgcatga gcagtacccg 960 tttctcccac gacgtgtgct gggcgtgcgc cttggtgaca tctcgctgca ggaggatgat 1020 gtgttgtcac agctggcgcg gcgtcgtgtg cggcagctaa gaaactccaa gacggcgatt 1080 gacgcacacg caactgaaga agagatgata aggcgcgcag aggagctggc tcgcaacgtg 1140 aagcttgtcg acgcataccg tgggaatggg aacgagtacg tgcgtgcctg caacccgttt 1200 ctcgtgtacg aggaccgcaa gtgcgtcctc ctgagtgagc tgccgcttgc cggtggcgac 1260 gtgtaccagg gcttgttccg ggattatctg actgcgctgg aggacgccga ggcaaatgca 1320 ccgcggatcg cggagctgga gaatgcgctt cggtcccgtg cggatgagtt ggcgctggag 1380 gtttgcgaga gggacgcgcg gttgttgcat tactcattcc tctcggccca ggatgttcct 1440 ggttggtctg aagcactgct gcatgacgcg gagtttcagc agctacgtga gcgttacgag 1500 gaactgagca aggatccaca ggggaacgcc gaggcattgc gtgagcttga ggatgcaatg 1560 gaggctcgga gcagagccat tgcggaagcg ttgcggactg cagagcgact aatccactga 1620 gcaggcgagg ctgaagacgc cgtcacaggc ggggtctggc gtgtccgcgg gtgatcgaat 1680 gcatggcagc gagcatgcgg atctcgcgca tgaaggggga agcacggctg gcggcaccat 1740 gaggggggca gagtctgtct ccaagagcag tgggaaacac tctcaaggtc ggtctcgcat 1800 gcgtctgtcg tagacctggg aggcgaggcc catgggacac actatgcctt tttgcccgat 1860 gtgatcaagg ggattgcgca ggaagagctg tacctggaag acgatgcgta cttcg 1915 8 400 DNA Trypanosoma cruzi Where any n is an unknown nucleic acid 8 ttaccaagct gagatagata aaaggctgca ggagcagctt gcccctgaga ggatgagggc 60 tctttccgca tttctttcgg agtgactttg actgttgcgc cgtttccgtg tcactatttc 120 tattgctttt aatttgctgg agaggcgcgt gtaggaggga aagagtagta acatggcaga 180 atcatcaaaa acgatgttgc gttagtagag aggagggaaa catcgagacg ttgagggttg 240 cgacggncaa aattatgtac atttacctga attaggataa gacttcatat ggcataaact 300 cgtggcgttg ttggtggtta taacaagcaa cggtgacgat gtcttaggct acactgctgc 360 actcaaagag ttttacaggt acttgcggat atttgttcct 400 9 936 DNA Trypanosoma cruzi 9 gcctcctgca actcgtgctg gcagcgttga agttcggcag aaatctcaac aaacgccttc 60 tgtccctcgg aaaccttccc gttaagagac acaagcagtt caatgagcga catggtcgct 120 tcggacacgt ccaatgcttt catggtttgt tccagccgcc gctgaaagtt atccacacat 180 gagaacaaca aagacaaatc taaatcggcg tcgccgtgct catacacatc aaacgccacc 240 gtctcgccca aaacattcaa aaagttcacc aaaaagttta caagcttact caaattgtca 300 cgaagtgagc taacggtaat ttctaaactt ccatttcttg cgtcatccct agccttcgcc 360 gcgactacct tctccttcca tagcactagc ttctcctcca ccaaacgaat accgctctcc 420 ttttctttca cagcaacctc acattccctt tcaatttcat tcaacctaat tggattattt 480 tcttaaacga cttgccgtgc cctcctcggg ctgatgaaag gcctcgccca gctgcgcacg 540 cagattcacg gtgtccgccc cgttctgctc ccggagagcg gccagttcct cggtggttcg 600 cttcagctcg cgatgcacct cctcgcgctg ctgcaaggcc tcgtccagct gcgcacgcag 660 attcacggtg tccgccccgc tctgctcccg gagagcgggc agttcctcgg tggttcgctt 720 cagctcgcga tgcacctcct cgcgctgctg caaggcctcg tccagctgcg cacgcagatt 780 cacggtgtcc gccccgctct gctcccggag agcgggcagt tcctcggtgg ttcgcttcag 840 ctcgcgacgc acctcctcgc gctgctggaa ggcctcgccc agctgcgcac gcagattcac 900 ggtgtccgcc cctctctgct cccggagggc gggcag 936 10 702 DNA Trypanosoma cruzi Where any n is an unknown nucleic acid 10 acttgaaaga ntgacccaat aatngggttc cttattgtgc caccccaaat aaacccgtaa 60 ccaatttgtg gctgggatgg atccccccac nctctttgac ncatgtcaag agtanatggg 120 acgtcaaagt cacttagaga gggattcatg ggtnccattg atcacaagag cctnctggaa 180 gacccccgtg aagataaccc aatgagattt atcgtctgca taagatcaca cgaggcggta 240 ttagcaatta tcttcacaga ttctttttct tgtgatggtg gcttgcggta gtttgtcatc 300 attgttttct gaatgcaatg aagcacacga cttgtaatac gttctccatg tctttcaatc 360 gtttccaacg cctccacaat gtctgcagga tccccaggaa ggtcagcagt catcagaagc 420 tcttcacatg aacgccgtaa actaggatca cgctcaacaa ggctagcaat cgcatttgcc 480 attctcggat tccacttgca aaaccactcc ggaagtttat ttccacgact gacctctgtc 540 ataatgttga acctctccct aaagccttta cccgccacgg caagccacat ctcaagagct 600 atcataccca ggctgtattc atccacttta aagtcgtagt cttcccctcg ctcttgctct 660 ggggcacagt acaacacaga acccaagttt cctgtaggac cg 702 11 510 DNA Trypanosoma cruzi 11 cgagtattcc tgtggaaatt gatattagaa accaggactt ttcttttctt gacccggcac 60 cggagggcat tcctattcag gacatacatc ttatgggaga ttctgcattt gccgcatctg 120 cgcgtgagcg catgaaactg aaaagaaatc ctgttgcgaa tgcgagcaag atcagtgccc 180 ttgaggagga gatggatcaa cgtgctcatg tattggctaa gcaggtgcgt gacaaagagc 240 gcactttcct tgatccagag cctgagggtg ttccacttga gttgctttca ttaaatgaaa 300 atgaggcctc acaggaattg gagcgagagc ttcgtgccct aaatcgcaaa ccccggaagg 360 atgccaaagc aatagttgct cttgaagatg atgtgcgtga cgaacacacg tgcttgccaa 420 ggagctaaag gaaaatgagc ggaacatctt tgttggctcc acagcctgag ggtgtgccgg 480 tgtctgagct gtcgttggat ttagacgagc 510 12 320 DNA Trypanosoma cruzi Where any n is an unknown nucleic acid 12 cggtcgtggc agagccaaag ccaccaacag caggtgccga cgtgtgcgcg gcagagccga 60 agccaccagc agcaggcgcc gaagtggtcg tggcagagcc aaagccacca gcagcaggtg 120 ccgacgtgtg cgcggcagag tcgaagccac caacagcagg tgccgacgtg gtcgtggcag 180 agccaaagtc accagtagta ggngccgacg tgtgngtggc agagncanag ncaccagtag 240 naggtgncga cgtngtcgtg gnagagncga ngtcaccagc aggaggtgnc gacgtntgng 300 nggnagaggc gatgtcacca 320 13 302 DNA Trypanosoma cruzi 13 atgcatctcc cccgtacatt attttgcgga aaattggatt tttacgggga ggtggggttc 60 gattggggtt ggtgtaatat aggtggagat ggagtgcagt gggataggat tagaatgtag 120 ttggtgtagt acagagttta tatagtatag tgttgatgtt attatacaat gaggtaagag 180 aatggagtga gaaagagtat gtttgttagt ttggttgtta atgttatgta ttcatgttat 240 cagtatatgt tgtatgtgta tggtgatagc ggtgggtgta gctgtatgtg gtaggttaga 300 gt 302 14 298 DNA Trypanosoma cruzi 14 cagtttcaat ttcctctcca cctgatcccg ctgttgcaaa agcgtccttg atgtatcctg 60 ctcctttgcc gctagcgcct cccttgctaa gcgcagttcc tcttgcagcc tcgcctgcac 120 ccgttccgcc tccattaatc tcttctcccc gattgcttct ttggcgcgta aatcctccag 180 ttccttctct atcaaagtgt gcctcccatt cctgatccgc gactcttcac aggcttcttg 240 ctccgcgtca cggagacgcc tcttgagagc ctcgttcttc tcttccaggt cttctggg 298 15 2144 DNA Trypanosoma cruzi 15 cgcggaattc ttaccaagct gagatagata aaaggctgca ggagcagctt gcccctgaga 60 ggatgaaggc tctttccaca tttctttggg agtgaccttg actgttgcgc cgtttccgtg 120 tcactatttc tattgctttt aaattgctgg agaggcgcgt gtaggagaga aagagtagta 180 acatggcgga atcatcaaaa acgatgttgc gtaagtagag aggagggaaa catcgagacg 240 ttgagggttg cgacggccaa gattatgtac atttacctga attaggataa gacttcatat 300 ggtataaagt cgtggcgttg ttggtggtta taacaagcaa cggtgacgat gtctcagtct 360 acactgctac aatcaaagag ttttacaggt acttgtggat atttgttcct gtgagtttgt 420 tttctattat aatttatttt gtctcaattt tttgtttccc cgcttcctac ggtctctttt 480 tttcttcgtt cttgaaattt caattattgc ttaaccacaa gcatccagta cttcaacctc 540 cccatcaaat ggtgtcgctg aagctgcagg ctcgtttggc ggcggacatt ctccgctgcg 600 gtcgccaccg tgtgtggctg gaccctaatg aggcctctga gatttccaat gcaaactcgc 660 gcaagagcgt gcgcaagttg atcaaggatg gtctgattat tcgcaagcct gtcaaggtgc 720 actcgcgctc ccgctggcgc cacatgaagg aggcgaagag catgggccgc cacgagggcg 780 ctgggcgccg cgagggtacc cgcgaagccc gcatgccgag caaggagctg tggatgcgcc 840 gtctgcgcat tctccgccgc ctgctgcgca agtaccgcga ggagaagaag attgaccgcc 900 acatttaccg cgagctgtac gtgaaggcga aggggaacgt gtttcgcaac aagcgtaacc 960 tcatggagca catccacaag gtgaagaacg agaagaagaa ggaaaggcag ctggctgagc 1020 agctcgcggc gaagcgcctg aaggatgagc agcaccgtca caaggcccgc aagcaggagc 1080 tgcgtaagcg cgagaaggac cgcgagcgtg cgcgtcgcga agatgctgcc gctgccgccg 1140 ccgcgaagca gaaagctgct gcgaagaagg ccgctgctcc ctctggcaag aagtccgcga 1200 aggctgctgc acccgcgaag gctgctgctg cacccgcgaa ggccgctgct ccacccgcga 1260 agaccgctgc tgcacccgcg aaggctgctg cacctgccaa ggctgctgct ccacccgcga 1320 aggctgctgc tccacccgcg aagaccgctg ctccacccgc gaagaccgct gctccacccg 1380 cgaaggctgc tgctccaccc gcgaaggccg ctgctccacc cgcgaaggcc gctgctccac 1440 ccgcgaaggc cgctgctgca cccgcgaagg ccgctgctgc acccgcgaag gctgctgctc 1500 cacccgcgaa ggccgctgct ccacccgcga aggctgctgc tccacccgcg aaggctgctg 1560 ctccacccgc gaaggctgct gctgctcccg ttggaaagaa ggctggtggc aagaagtgaa 1620 gcgcgcacta gtacgaccaa cttgtttttt tttttggtat ttaatatttt ctgaggaaga 1680 agtgggtatt gagggtcttt ctttccgcgt ttgtgttggt ttgtggtgtt cgtgacatta 1740 tagtagatcc aaagtattct tcagtgtccc ttttcctttt ctccatcctt tttcctattt 1800 tttgtttgtc ttctctacga tctttgttgt cgtgtgacct ccgctgtatg gaactgacgg 1860 ccggcgttgt gagagacgat gtcgcacgtc acggcggacc tggagtattt taaatgtgac 1920 atgtgcgggg tgtatctgca caaagacatc ttttgcgacc atcgacgtga gtgtaaaggc 1980 cttgattcga aagagctgaa gaagagccag tgtcgtcaga tcgggatggc attagacaag 2040 gaggcacggc accgaattgc gtcacgaatg gctgatggag caactctcgt gcctgtcgag 2100 cttgcagaac gacatcaaca ggcgcgtgtg cggcgtaatg tggc 2144 16 456 DNA Trypanosoma cruzi 16 tgtgctgcag aaggagaggg atgaagccgt ggcggagaat gcccagctgc agaaggagag 60 ggatgacgcc gtggcggaga atgcccagct gcagaaggag agggatgacg ccgtggcgga 120 gaatgcccag ctgcagaagg agagggatga cgccgtggcg gagaatgccc agctgcagaa 180 ggagagggat gacgccgtgg cggagaatgc ccagctgcag aaggagaggg acgaagccgt 240 ggcggagaat gcccagctgc agagggagag ggatgacgcc gtggcggagg atgcccagct 300 gcagaaggag agggatgaag ccgtggcgga gaatgcccag ctgcagaggg agagggatga 360 agccgtggcg gagaatgccc agctgcagaa ggagagggat gacgtcgtgg cggagaatgc 420 ccagctgcag aaggagaggg atgacgccgt ggcgga 456 17 2446 DNA Trypanosoma cruzi Where any n is an unknown nucleic acid 17 tgaaggccgt tgatcctttt cagggaacga caccgccgcc ctataaatgg caagaaatga 60 ctggatctga ggcggcagcc ggctcgcttt gtgtacccag ccttgctgag gtggccggcg 120 gtgtgtttgc cgttgctgaa gctcagcgca gtgaaaggga cgaagcctgc ggccatgctg 180 cgattgcaac aacgcacatt gagacgggcg gtggtggctc aaaggcgatc tcggcgatgg 240 atgcaggcgt ttttctcgta gaacttgtgg atgccgccag tggtacgatc aggacacgag 300 aaaagatgca gccaacgaca attgtgagcg gcgacactat ctacatggcc cttggggact 360 acgagaagaa gacgtctggg ggtcgggctg ccgatgcaga tggctggagg cttttactga 420 tgaggggaac tctcactgag gatggtgggc agaagaaaat catgtggggt gatatccgtg 480 cagtggaccc tgtggccatc gggcttactc aattcctgaa gagggtgatc ggtggcggag 540 gatcgggtgt tgtgacgaag aacggttacc ttgtgcttcc catgcaggca gtagaaaagg 600 atggaaggag tgttgtactg tccatgcgtt tcaacatgcg tatagaagca tgcgagctct 660 cgtccggtac gacaggtagt aactgcaagg aaccatccat cgcgaatttg gaaggaaatc 720 taattttaat tacttcttgc gctgccggct actacgaagt attcaggtcc cttgactctg 780 ggacaagttg ggaaatgagt ggtaggccaa ttagtcgcgt gtggggcaac tcgtatggtc 840 gaaaagggta tggcgttcgc tgtggcctca ccaccgtaac cattgaggga agggaagtgc 900 tgcttgttac cacgccagtg tatttggagg agaaaaatgg taggggtcgg cttcatcttt 960 gggtgacgga cggtgcacgt gtgcatgatg ctgggccgat atccgatgca gctgatgacg 1020 ctgctgccag ttccctgttg tatagcagtg ggggcaatct gatttcgctg tacgagaata 1080 agagtgaggg gtcatacggt cttgttgctg tgcacgtgac tacgcagctg gagcggataa 1140 agactgtgtt gaagaggtgg caggagttgg atgaagccct aagaacgtgc agatccactg 1200 ccactatcga cccggtgaga aggggcatgt gtattcgtcc cattcttact gacgggcttg 1260 ttggctattt gtctggtctg tcgactggga gtgagtggat ggacgagtac ctctgcgtga 1320 acgcaactgt tcatgggacg gtgagagggt tctccaatgg agtgacgttt gaaggacccg 1380 gagcaggggc ggggtggcct gttgcccgaa gtggacagaa tcaaccgtac catttcttac 1440 acaaaacgtt cactctagtg gtgatggcgg tcatccacga taggccgaag aaacgcaccc 1500 ccattccttt gattcgtgtg gtgatggatg acaatgacaa gactgtgcta tttggtgtgt 1560 tttacaccca tgatgggagg tggatgactg taattcatag tggcggtaga caaatacttt 1620 caacagggtg ggacccagaa aaaccgtgtc aggtagtgct gcgacacgac acgggccatt 1680 gggatttcta cgttaacgcg aggaaggctt actttggcac ctacaagggt ctcttctcca 1740 aacaaacagt atttcacaca tccaattcca cggggagagt ggggaagttg cagagtccag 1800 ccatttgtca ctcttcaacg cccgtttgta taaccgaaga ctcaattcca agcatctaag 1860 atggctcatg gtcggcgaga caggcccaaa atacgatgat ggcagctctt attctgcgag 1920 tgcgtccgag gaaggaagca gaggtggcag ctccatgccc gcgggtacgt ccgaggaagg 1980 aagcagaggt ggcagctcca tgcctgcggg tacgtccgag gaaggaagca gaggaggcag 2040 ctccatgcct gcgggtacgt ccgaggaagg aagcagagga ggcagctcca tgcctgcggg 2100 tacgtccgag gaaggaagca gaggtggcag ctccatgcct gcgggcactt ccgaagaagg 2160 aagcagaagt ggcanctcca tgccttcggg ctcttccgaa gaaggaagca gaagaggccg 2220 ctccctgcct tcgggttctt ccgaaggaag gaagcagagg aggccctccc tgcctgcggg 2280 ttcttccgaa gaaggaaaca gaagtggcnc tccatgcccg cgggttcttc cgaggaagga 2340 accagaagaa gcnctccctg cccgcnggtt cntccnaaga aagaaacana agttggccnc 2400 tcccngcccc nngtttcttc cnaangaaag aaacaaaagt ggcccc 2446 18 345 DNA Trypanosoma cruzi 18 gggtacgtcc gaggaaggaa gcagaggtgg cagctccatg cctgcgggta cgtccgagga 60 aggaagcaga ggtgtcagct ccatgcctgc gggtacgtcc gaggaaggaa acagaggagg 120 caactccatg cctgcgggta cgtccgagga aggaagcaga ggtggcagct ccatgccttc 180 gggcacgtcc gaggaaggaa gcagaggtgg cagctccatg ccttcgggta cgtccgagga 240 aggaagcaga ggaggcagct ccatgcctgc gggtacgtcc gaggaaggaa gcagaggtgg 300 cagctccatg cccgcgggta cgtccgagga aggaagcaga ggccg 345 19 835 DNA Trypanosoma cruzi 19 ggcacgagct gtactatatt gtaggagagc agccatgggt atcgttcgca gccgcctgca 60 taaacgcaag atcaccggtg gaaagacgaa gatccaccgg aagcgcatga aggccgaact 120 cggccgtctt cccgcgcaca cgaagcttgg cgcccgccgc gtgagtcccg tccgcgcccg 180 cggtgggaac ttcaagctcc gcggtcttcg cctggacacc ggcaattttg cgtggagcac 240 agaagccatt gctcagcggg cccgtatcct cgacgttgtg tacaacgcca cttctaacga 300 gctggtgcgc acgaagacgc ttgtgaagaa ctgcattgtt gtggtggacg ccgcgccctt 360 caagttatgg tacgcgaagc actacggtat cgaccttgag ccgcgaagag caagaagacg 420 ctgcagagca cgacggagaa gaagaagtcg aagaagacct cacacgccat gactgagaag 480 tacgacgtca agaaggcctc cgacgagctg aagcgcaagt ggatgctccg ccgcgagaac 540 cacaagattg agaaggcagt tgctgatcag ctcaaggagg gccgtctgct cggccgcatc 600 acgagccgcc ctggccagac agcccgcgcc gatggtgcac tgctggaggg cgccgaactg 660 cagttctatc tgaagaagct cgagaagaag aagcggtaga gaaggatgtt cgggagacgg 720 gaggaggcgc caccaccacc actcatggtg atgcacccac tacctacttt gttttcattt 780 tttgttttac ctctaatttt ttaggccaga gggggggaaa aaaaaaaaaa aaaaa 835 20 555 DNA Trypanosoma cruzi 20 ggcacgagaa aaaagaaaac aaacaaataa aatcaaaaac agtaaatcca tcacttcaac 60 aatgagcatt gagagcgcct tttacgcctt tgcctccttt ggtggtgcgc ccacgaaaga 120 gatggacaat gctcacttct ccaagatgct gaaggagacg aaggtcattg gaaagcaatt 180 caccagcacc gacgccgatc ttctcttcaa caaagtgaag gcaaagggag cccgcaaaat 240 tacattgtcg gattttgttg acaaggctgt tcctgagatt gcatcaaagt taaagaagtc 300 cgcggaggaa ttgatcgcag atatttcaag ttgctctccc gaggcacgcg caaccaaggc 360 cgatgcagtt aagttccacg acgataagaa catgtacact ggtgtctaca aggccggcgg 420 gccaacaaac gtggatcgca actccggctc cctttcaggt gtcgtggatc gccgtgtggc 480 gcagactgac gttcgtggca cgactgcttc ccagaagtaa agagggaaac gaaatggaaa 540 aaaaaaaaaa aaaaa 555 21 936 DNA Trypanosoma cruzi 21 ggcacgagag ctctcttcgt cagtcatgac gctcgggaag aacaagcgca tcagcaaggg 60 cggcaagcgc ggcaagaaga agacccagga gacgatgagc cgcaaggagt ggtacgatgt 120 ggttgccccc aagaactttg aggtgcgcca gtttggcaag accatctgca acaagaccca 180 gggcacaaag atcgcggcgg actacctgcg cgggcgcgtg tacgaaagca accttgcgga 240 tctgaacaag acgcaaggcg acgacgacgc ctaccgcaag gtgaagtttg ttgtgcagga 300 ggtgcagggc cgcaacctgc ttacgcagtt ccacagcatg gaaatgacat ctgaccgcgt 360 gtactttttg ctgcgcaagt ggtgcacgac gatcgaggcg gcagtggaga cgaagactgc 420 ggacggctac accctgcgcc tcttcgtgat tgccttcacg aagaagcaga gcaaccagct 480 gtcgaagaac tgctatgcca agacgcgcct ggtgaagtgg gtgcgccatc gcatcacgaa 540 cctcatccgc cagcgcctgt cgaaggtgaa catcaacgag gcggtgacgc tgctgacacg 600 caacatcctg cgcgatcgtc tggcaaagcg ctgcaacccc atcgtgccgc tgcgcgatct 660 ccgcatccgc aaggtgaagg tggtccgcac cccccggttt tgacgcccag gcgcttctga 720 atgcacacgg cgagatcccc gcctcggctg agggtgaggc acgcgtcgtc gaggaagccc 780 aagaggctcc cgccgctgaa gccacagcct aagccttcca tgtggaggaa ggatgtgtga 840 tgtgaaagct ctttgttctt ttttctttct attttgaaac ggtgattccg catatatata 900 ttaaaaaaaa aaaaaaaaaa aaaaaaaaaa aaaaaa 936 22 581 DNA Trypanosoma cruzi 22 gtactatatt gttgctatta acacactgtt aggaacgcga aaccatgcag atcttcgtga 60 agacactgac gggcaagacg atcgcgctcg aggtggaatc cagcgacacc attgagaacg 120 tgaaggcgaa gatccaggac aaggagggca ttccgccgga ccagcagcgc ctgatcttcg 180 ctggcaagca gctggaggac ggccgcacgc tcgcagacta caacatccag aaggagtcca 240 cgctgcacct tgtgctgcgc ctgcgcggtg gtgtgatgga gccgacactt gaggccctgg 300 cgaagaagta caactgggag aagaaggtat gccgccgctg ctacgcccgt ctgccggtgc 360 gtgcgtccaa ctgccgcaag aaggcatgtg gccactgctc caacctccgc atgaagaaga 420 agctgcggta gtctgcgatg ctgtggaccg acgcattgaa atacacaccg tcttcggcgt 480 tccttttttt tatatgtctt tttttttatt gagaagatgt cttgtttgtt gttgtttttt 540 tttcaaaaaa aaaaaaaaaa aaaaaaaaaa aaaaaaaaaa a 581 23 30 PRT Trypanosoma cruzi 23 Leu Pro Pro Leu Leu Pro Ser Ser Asp Val Pro Glu Gly Met Glu Leu 1 5 10 15 Pro Pro Leu Leu Pro Ser Ser Asp Ile Pro Glu Gly Met Glu 20 25 30 24 90 PRT Trypanosoma cruzi 24 Gly Cys Leu Leu Cys Phe Leu Pro Arg Thr Cys Pro Lys Ala Trp Ser 1 5 10 15 Cys Leu Leu Cys Phe Leu Pro Arg Thr Tyr Pro Lys Ala Trp Ser Cys 20 25 30 His Leu Cys Phe Leu Pro Arg Thr Tyr Pro Arg Ala Trp Ser Cys His 35 40 45 Leu Cys Phe Leu Pro Arg Thr Cys Pro Lys Ala Trp Ser Cys His Leu 50 55 60 Cys Phe Leu Pro Arg Thr Tyr Pro Arg Ala Trp Ser Cys His Leu Cys 65 70 75 80 Phe Leu Pro Arg Thr Tyr Pro Arg Val Trp 85 90 25 90 PRT Trypanosoma cruzi 25 Ala Ala Ser Ser Ala Ser Phe Leu Gly Arg Ala Arg Arg His Gly Ala 1 5 10 15 Ala Ser Ser Ala Ser Phe Leu Gly His Thr Arg Arg His Gly Ala Ala 20 25 30 Thr Ser Ala Ser Phe Leu Gly Arg Thr Arg Gly His Gly Ala Ala Thr 35 40 45 Ser Ala Ser Phe Leu Gly Arg Ala Arg Arg His Gly Ala Ala Thr Ser 50 55 60 Ala Ser Phe Leu Gly Arg Thr Arg Gly His Gly Ala Ala Thr Ser Ala 65 70 75 80 Ser Phe Leu Gly Arg Thr Arg Gly His Gly 85 90 26 40 PRT Trypanosoma cruzi 26 Ser Val Pro Gly Lys Arg Leu Arg Asn Ser His Gly Lys Ser Leu Arg 1 5 10 15 Asn Val His Gly Lys Arg Pro Lys Asn Glu His Gly Lys Arg Leu Arg 20 25 30 Ser Val Pro Asn Glu Arg Leu Arg 35 40 27 40 PRT Trypanosoma cruzi 27 Glu Ala Glu Glu Leu Ala Arg Gln Glu Ser Glu Glu Arg Ala Arg Gln 1 5 10 15 Glu Ala Glu Glu Arg Ala Trp Gln Glu Ala Glu Glu Arg Ala Gln Arg 20 25 30 Glu Ala Glu Glu Arg Ala Gln Arg 35 40 28 56 PRT Trypanosoma cruzi 28 Ser Trp Gln Ser Gln Ser His Gln Gln Gln Val Pro Thr Cys Ala Arg 1 5 10 15 Gln Ser Arg Ser His Gln Gln Gln Ala Pro Lys Trp Ser Trp Gln Ser 20 25 30 Gln Ser His Gln Gln Gln Val Pro Thr Cys Ala Arg Gln Ser Arg Ser 35 40 45 His Gln Gln Gln Val Pro Thr Trp 50 55 29 56 PRT Trypanosoma cruzi 29 Gly Arg Gly Arg Ala Lys Ala Thr Asn Ser Arg Cys Arg Arg Val Arg 1 5 10 15 Gly Arg Ala Glu Ala Thr Ser Ser Arg Arg Arg Ser Gly Arg Gly Arg 20 25 30 Ala Lys Ala Thr Ser Ser Arg Cys Arg Pro Val Arg Gly Arg Ala Glu 35 40 45 Ala Thr Asn Ser Arg Cys Arg Arg 50 55 30 56 PRT Trypanosoma cruzi 30 Val Val Ala Glu Pro Lys Pro Pro Thr Ala Gly Ala Asp Val Cys Ala 1 5 10 15 Ala Glu Pro Lys Pro Pro Ala Ala Gly Ala Glu Val Val Val Ala Glu 20 25 30 Pro Lys Pro Pro Ala Ala Gly Ala Asp Val Cys Ala Ala Glu Pro Lys 35 40 45 Pro Pro Thr Ala Gly Ala Asp Val 50 55 31 7 PRT Trypanosoma cruzi 31 Pro Pro Ala Lys Ala Ala Ala 1 5 32 151 PRT Trypanosoma cruzi 32 Val Leu Gln Lys Glu Arg Asp Glu Ala Val Ala Glu Asn Ala Gln Leu 1 5 10 15 Gln Lys Glu Arg Asp Asp Ala Val Ala Glu Asn Ala Gln Leu Gln Lys 20 25 30 Glu Arg Asp Asp Ala Val Ala Glu Asn Ala Gln Leu Gln Lys Glu Arg 35 40 45 Asp Asp Ala Val Ala Glu Asn Ala Gln Leu Gln Lys Glu Arg Asp Asp 50 55 60 Ala Val Ala Glu Asn Ala Gln Leu Gln Lys Glu Arg Asp Glu Ala Val 65 70 75 80 Ala Glu Asn Ala Gln Leu Gln Arg Glu Arg Asp Asp Ala Val Ala Glu 85 90 95 Asp Ala Gln Leu Gln Lys Glu Arg Asp Glu Ala Val Ala Glu Asn Ala 100 105 110 Gln Leu Gln Arg Glu Arg Asp Glu Ala Val Ala Glu Asn Ala Gln Leu 115 120 125 Gln Lys Glu Arg Asp Asp Val Val Ala Glu Asn Ala Gln Leu Gln Lys 130 135 140 Glu Arg Asp Asp Ala Val Ala 145 150 33 140 PRT Trypanosoma cruzi 33 Cys Arg Arg Arg Gly Met Lys Pro Trp Arg Arg Met Pro Ser Cys Arg 1 5 10 15 Arg Arg Gly Met Thr Pro Trp Arg Arg Met Pro Ser Cys Arg Arg Arg 20 25 30 Gly Met Thr Pro Trp Arg Arg Met Pro Ser Cys Arg Arg Arg Gly Met 35 40 45 Thr Pro Trp Arg Arg Met Pro Ser Cys Arg Arg Arg Gly Met Thr Pro 50 55 60 Trp Arg Arg Met Pro Ser Cys Arg Arg Arg Gly Thr Lys Pro Trp Arg 65 70 75 80 Arg Met Pro Ser Cys Arg Gly Arg Gly Met Thr Pro Trp Arg Arg Met 85 90 95 Pro Ser Cys Arg Arg Arg Gly Met Lys Pro Trp Arg Arg Met Pro Ser 100 105 110 Cys Arg Gly Arg Gly Met Lys Pro Trp Arg Arg Met Pro Ser Cys Arg 115 120 125 Arg Arg Gly Met Thr Ser Trp Arg Arg Met Pro Ser 130 135 140 34 60 PRT Trypanosoma cruzi 34 Gly Tyr Val Arg Gly Arg Lys Gln Arg Trp Gln Leu His Ala Phe Gly 1 5 10 15 Tyr Val Arg Gly Arg Lys Gln Arg Trp Gln Leu His Ala Phe Gly Tyr 20 25 30 Val Arg Gly Arg Lys Gln Arg Arg Gln Leu His Ala Cys Gly Tyr Val 35 40 45 Arg Gly Arg Lys Gln Arg Trp Gln Leu His Ala Cys 50 55 60 35 60 PRT Trypanosoma cruzi 35 Gly Thr Ser Glu Glu Gly Ser Arg Gly Gly Ser Ser Met Pro Ser Gly 1 5 10 15 Thr Ser Glu Glu Gly Ser Arg Gly Gly Ser Ser Met Pro Ser Gly Thr 20 25 30 Ser Glu Glu Gly Ser Arg Gly Gly Ser Ser Met Pro Ala Gly Thr Ser 35 40 45 Glu Glu Gly Ser Arg Gly Gly Ser Ser Met Pro Ala 50 55 60 36 60 PRT Trypanosoma cruzi 36 Val Arg Pro Arg Lys Glu Ala Glu Val Ala Ala Pro Cys Leu Arg Val 1 5 10 15 Arg Pro Arg Lys Glu Ala Glu Val Ala Ala Pro Cys Leu Arg Val Arg 20 25 30 Pro Arg Lys Glu Ala Glu Glu Ala Ala Pro Cys Leu Arg Val Arg Pro 35 40 45 Arg Lys Glu Ala Glu Val Ala Ala Pro Cys Leu Arg 50 55 60 37 639 PRT Trypanosoma cruzi Where any Xaa is an independently selected amino acid 37 Asp Ala Ser Val Val Asp Leu Gly Gly Glu Ala His Gly Thr His Tyr 1 5 10 15 Ala Phe Leu Pro Asp Val Ile Lys Gly Ile Ala Gln Glu Glu Leu Tyr 20 25 30 Leu Glu Asp Asp Ala Tyr Phe Gln Glu Leu Leu Ala Arg Tyr Lys Glu 35 40 45 Leu Val Pro Val Gly Ala Glu Pro Thr Glu Pro Arg Ala Lys Gln Leu 50 55 60 Arg Glu Gln Met Arg Ile Arg Ala Gly Gln Leu Ala Val Asp Thr Arg 65 70 75 80 Lys Leu His Ala Ala Glu Glu Arg Ala Ala Ser Arg Met Ala Thr Leu 85 90 95 Tyr Pro Phe Val Gly Ser Ala Pro Leu Gly Val Ala Leu Trp Asn Ile 100 105 110 Pro Val Glu Ala Asp Glu Glu Phe Cys Ala Leu Leu Leu Lys Arg Glu 115 120 125 Glu Ala Leu Ala Gly Lys Ser Gly Ser Val His Glu Val Glu Ser Ala 130 135 140 Leu Ser Ala Arg Ala Glu Ala Met Ala Lys Ala Val Leu Glu Glu Glu 145 150 155 160 Glu Ala Leu Ala Ala Ala Phe Pro Phe Leu Gly Arg Ser Val Lys Gly 165 170 175 Ala Pro Leu Arg Glu Leu Ala Leu Met Ser Asp Pro Asn Phe Ala Glu 180 185 190 Leu Ala Thr Arg His Ala Gln Glu Ala Thr Ser Gly Asp Ala Ala Gly 195 200 205 Ile Leu Arg Leu Glu Gln Glu Leu Arg Asp Gln Ala Cys Arg Ile Ala 210 215 220 Arg Glu Val Arg Val Ala Arg Arg Leu Asp Ala Xaa Arg Asn Glu Asp 225 230 235 240 Leu His Glu Arg Tyr Pro Phe Leu Pro Glu Glu Pro Val Arg Gly Ile 245 250 255 Leu Leu Gly Ala Val Arg Pro Val Gln Gln Pro Ala Phe Arg Glu Leu 260 265 270 Ser Asn Lys Leu Asp Glu Gln Arg Arg Asp Pro Thr Arg Asn Ala Ala 275 280 285 Ala Ile Arg Thr Thr Glu Glu Gln Met Thr Ala Leu Val Val Arg Leu 290 295 300 Ala Glu Glu Arg Ala Glu Ala Thr Glu Arg Ala His Glu Gln Tyr Pro 305 310 315 320 Phe Leu Pro Arg Arg Val Leu Gly Val Arg Leu Gly Asp Ile Ser Leu 325 330 335 Gln Glu Asp Asp Val Leu Ser Gln Leu Ala Arg Arg Arg Val Arg Gln 340 345 350 Leu Arg Asn Ser Lys Thr Ala Ile Asp Ala His Ala Thr Glu Glu Glu 355 360 365 Met Ile Arg Arg Ala Glu Glu Leu Ala Arg Asn Val Lys Leu Val Asp 370 375 380 Ala Tyr Arg Gly Asn Gly Asn Glu Tyr Val Arg Ala Cys Asn Pro Phe 385 390 395 400 Leu Val Tyr Glu Asp Arg Lys Cys Val Leu Leu Ser Glu Leu Pro Leu 405 410 415 Ala Gly Gly Asp Val Tyr Gln Gly Leu Phe Arg Asp Tyr Leu Thr Ala 420 425 430 Leu Glu Asp Ala Glu Ala Asn Ala Pro Arg Ile Ala Glu Leu Glu Asn 435 440 445 Ala Leu Arg Ser Arg Ala Asp Glu Leu Ala Leu Glu Val Cys Glu Arg 450 455 460 Asp Ala Arg Leu Leu His Tyr Ser Phe Leu Ser Ala Gln Asp Val Pro 465 470 475 480 Gly Trp Ser Glu Ala Leu Leu His Asp Ala Glu Phe Gln Gln Leu Arg 485 490 495 Glu Arg Tyr Glu Glu Leu Ser Lys Asp Pro Gln Gly Asn Ala Glu Ala 500 505 510 Leu Arg Glu Leu Glu Asp Ala Met Glu Ala Arg Ser Arg Ala Ile Ala 515 520 525 Glu Ala Leu Arg Thr Ala Glu Xaa Thr Asn Xaa Thr Glu Gln Ala Arg 530 535 540 Leu Lys Thr Pro Ser Gln Ala Gly Ser Gly Val Ser Ala Gly Asp Arg 545 550 555 560 Met His Gly Ser Glu His Ala Asp Leu Ala His Glu Gly Gly Ser Thr 565 570 575 Ala Gly Gly Thr Met Arg Gly Ala Glu Ser Val Ser Lys Ser Ser Gly 580 585 590 Lys His Ser Xaa Arg Ser Val Ser His Ala Ser Val Val Asp Leu Gly 595 600 605 Gly Glu Ala His Gly Thr His Tyr Ala Phe Leu Pro Asp Val Ile Lys 610 615 620 Gly Ile Ala Gln Glu Glu Leu Tyr Leu Glu Asp Asp Ala Tyr Phe 625 630 635 38 231 PRT Trypanosoma cruzi 38 Ala Arg Ala Val Leu Tyr Cys Arg Arg Ala Ala Met Gly Ile Val Arg 1 5 10 15 Ser Arg Leu His Lys Arg Lys Ile Thr Gly Gly Lys Thr Lys Ile His 20 25 30 Arg Lys Arg Met Lys Ala Glu Leu Gly Arg Leu Pro Ala His Thr Lys 35 40 45 Leu Gly Ala Arg Arg Val Ser Pro Val Arg Ala Arg Gly Gly Asn Phe 50 55 60 Lys Leu Arg Gly Leu Arg Leu Asp Thr Gly Asn Phe Ala Trp Ser Thr 65 70 75 80 Glu Ala Ile Ala Gln Arg Ala Arg Ile Leu Asp Val Val Tyr Asn Ala 85 90 95 Thr Ser Asn Glu Leu Val Arg Thr Lys Thr Leu Val Lys Asn Cys Ile 100 105 110 Val Val Val Asp Ala Ala Pro Phe Lys Leu Trp Tyr Ala Lys His Tyr 115 120 125 Gly Ile Asp Leu Asp Ala Ala Lys Ser Lys Lys Thr Leu Gln Ser Thr 130 135 140 Thr Glu Lys Lys Lys Ser Lys Lys Thr Ser His Ala Met Thr Glu Lys 145 150 155 160 Tyr Asp Val Lys Lys Ala Ser Asp Glu Leu Lys Arg Lys Trp Met Leu 165 170 175 Arg Arg Glu Asn His Lys Ile Glu Lys Ala Val Ala Asp Gln Leu Lys 180 185 190 Glu Gly Arg Leu Leu Ala Arg Ile Thr Ser Arg Pro Gly Thr Ala Arg 195 200 205 Ala Asp Gly Ala Leu Leu Glu Gly Ala Glu Leu Gln Phe Tyr Leu Lys 210 215 220 Lys Leu Glu Lys Lys Lys Arg 225 230 39 172 PRT Trypanosoma cruzi 39 Ala Arg Glu Lys Arg Lys Gln Thr Asn Lys Ile Lys Asn Ser Lys Ser 1 5 10 15 Ile Thr Ser Thr Met Ser Glu Glu Ser Ala Phe Tyr Ala Phe Ala Ser 20 25 30 Phe Gly Gly Ala Pro Thr Lys Glu Met Asp Asn Ala His Phe Ser Lys 35 40 45 Met Leu Lys Glu Thr Lys Val Ile Gly Lys Gln Phe Thr Ser Thr Asp 50 55 60 Ala Asp Leu Leu Phe Asn Lys Val Lys Ala Lys Gly Ala Arg Lys Ile 65 70 75 80 Thr Leu Ser Asp Phe Val Asp Lys Ala Val Pro Glu Ile Ala Ser Lys 85 90 95 Leu Lys Lys Ser Ala Glu Glu Leu Ile Ala Asp Ile Ser Ser Cys Ser 100 105 110 Pro Glu Ala Arg Ala Thr Lys Ala Asp Ala Val Lys Phe His Asp Asp 115 120 125 Lys Asn Met Tyr Thr Gly Val Tyr Lys Ala Gly Gly Pro Thr Asn Val 130 135 140 Asp Arg Asn Ser Gly Ser Leu Ser Gly Val Val Asp Arg Arg Val Ala 145 150 155 160 Gln Thr Asp Val Arg Gly Thr Thr Ala Ser Gln Lys 165 170 40 233 PRT Trypanosoma cruzi 40 Ala Arg Glu Leu Ser Ser Ser Val Met Thr Leu Gly Lys Asn Lys Arg 1 5 10 15 Ile Ser Lys Gly Gly Lys Arg Gly Lys Lys Lys Thr Gln Glu Thr Met 20 25 30 Ser Arg Lys Glu Trp Tyr Asp Val Val Ala Pro Lys Asn Phe Glu Val 35 40 45 Arg Gln Phe Gly Lys Thr Ile Cys Asn Lys Thr Gln Gly Thr Lys Ile 50 55 60 Ala Ala Asp Tyr Leu Arg Gly Arg Val Tyr Glu Ser Asn Leu Ala Asp 65 70 75 80 Leu Asn Lys Thr Gln Gly Asp Asp Asp Ala Tyr Arg Lys Val Lys Phe 85 90 95 Val Val Gln Glu Val Gln Gly Arg Asn Leu Leu Thr Gln Phe His Ser 100 105 110 Met Glu Met Thr Ser Asp Arg Val Tyr Phe Leu Leu Arg Lys Trp Cys 115 120 125 Thr Thr Ile Glu Ala Ala Val Glu Thr Lys Thr Ala Asp Gly Tyr Thr 130 135 140 Leu Arg Leu Phe Val Ile Ala Phe Thr Lys Lys Gln Ser Asn Gln Leu 145 150 155 160 Ser Lys Asn Cys Tyr Ala Lys Thr Arg Leu Val Lys Trp Val Arg His 165 170 175 Arg Ile Thr Asn Leu Ile Arg Gln Arg Leu Ser Lys Val Asn Ile Asn 180 185 190 Glu Ala Val Thr Leu Leu Thr Arg Asn Ile Leu Arg Asp Arg Leu Ala 195 200 205 Lys Arg Cys Asn Pro Ile Val Pro Leu Arg Asp Leu Arg Ile Arg Lys 210 215 220 Val Lys Val Val Arg Thr Pro Arg Phe 225 230 41 128 PRT Trypanosoma cruzi 41 Met Gln Ile Phe Val Lys Thr Leu Thr Gly Lys Thr Ile Ala Leu Glu 1 5 10 15 Val Glu Ser Ser Asp Thr Ile Glu Asn Val Lys Ala Lys Ile Gln Asp 20 25 30 Lys Glu Gly Ile Pro Pro Asp Gln Gln Arg Leu Ile Phe Ala Gly Lys 35 40 45 Gln Leu Glu Asp Gly Arg Thr Leu Ala Asp Tyr Asn Ile Gln Lys Glu 50 55 60 Ser Thr Leu His Leu Val Leu Arg Leu Arg Gly Gly Val Met Glu Pro 65 70 75 80 Thr Leu Glu Ala Leu Ala Lys Lys Tyr Asn Trp Glu Lys Lys Val Cys 85 90 95 Arg Arg Cys Tyr Ala Arg Leu Pro Val Arg Ala Ser Asn Cys Arg Lys 100 105 110 Lys Ala Cys Gly His Cys Ser Asn Leu Arg Met Lys Lys Lys Leu Arg 115 120 125 42 145 PRT Trypanosoma cruzi Where any Xaa is an independently selected amino acid 42 Arg Leu Pro Pro Leu Leu Pro Ser Ser Asp Val Pro Glu Gly Met Glu 1 5 10 15 Leu Pro Pro Leu Leu Pro Ser Ser Asp Ile Pro Glu Gly Met Glu Leu 20 25 30 Pro Pro Leu Leu Pro Ser Ser Asp Val Pro Ala Gly Met Glu Leu Thr 35 40 45 Pro Leu Leu Pro Ser Ser Asp Val Pro Glu Gly Met Glu Leu Pro Pro 50 55 60 Leu Leu Pro Ser Ser Asp Val Pro Ala Gly Met Glu Leu Pro Pro Leu 65 70 75 80 Xaa Pro Ser Ser Asp Val Pro Ala Gly Met Glu Leu Pro Pro Leu Leu 85 90 95 Pro Ser Ser Asp Val Pro Ala Xaa Ile Glu Leu Pro Pro Leu Ile Ser 100 105 110 Xaa Leu Gly Arg Thr Xaa Arg Xaa Gly Asp Xaa Ser Ser Xaa Ser Cys 115 120 125 Leu Gly Arg Xaa Xaa Arg Xaa Arg Xaa Ala Pro Leu Xaa Pro Xaa Ser 130 135 140 Glu 145 43 186 PRT Trypanosoma cruzi 43 Glu Lys Glu Arg Arg Phe Pro Thr Lys Thr Ala Arg Ala Asp Pro Thr 1 5 10 15 Thr Thr Lys Gln Leu Ile Ile Arg Ala Leu Gln Asn Ile Ser Leu Ala 20 25 30 Phe Gly Ile Glu Pro Ser Ser Thr Val Lys Tyr Ala Glu Ser Thr Gln 35 40 45 Glu Glu Asn Gly Lys Arg Ser Gln Ser Glu Ala Glu Glu Arg Ala Arg 50 55 60 Arg Glu Ala Glu Glu Arg Ala Arg Arg Glu Ala Glu Glu Arg Ala Gln 65 70 75 80 Arg Glu Ala Glu Glu Arg Ala Gln Arg Glu Ala Glu Glu Arg Ala Arg 85 90 95 Arg Glu Ala Glu Lys Arg Ala Arg Arg Glu Ala Lys Glu Arg Ala Trp 100 105 110 Gln Glu Ala Glu Glu Arg Ala Gln Arg Glu Ala Glu Glu Arg Ala Arg 115 120 125 Arg Glu Ala Glu Glu Arg Ala Arg Arg Glu Val Glu Glu Arg Ala Arg 130 135 140 Gln Glu Ala Glu Glu Leu Ala Arg Gln Glu Ser Glu Glu Arg Ala Arg 145 150 155 160 Gln Glu Ala Glu Glu Arg Ala Trp Gln Glu Ala Glu Glu Arg Ala Gln 165 170 175 Arg Glu Ala Glu Glu Arg Ala Gln Arg Ala 180 185 44 106 PRT Trypanosoma cruzi Where any Xaa is an independently selected amino acid 44 Gly Arg Gly Arg Ala Lys Ala Thr Asn Ser Arg Cys Arg Arg Val Arg 1 5 10 15 Gly Arg Ala Glu Ala Thr Ser Ser Arg Arg Arg Ser Gly Arg Gly Arg 20 25 30 Ala Lys Ala Thr Ser Ser Arg Cys Arg Arg Val Arg Gly Arg Val Glu 35 40 45 Ala Thr Asn Ser Arg Cys Arg Arg Gly Arg Gly Arg Ala Lys Val Thr 50 55 60 Ser Ser Arg Xaa Arg Arg Val Xaa Gly Arg Xaa Xaa Xaa Thr Ser Xaa 65 70 75 80 Arg Xaa Arg Arg Xaa Arg Gly Arg Xaa Xaa Val Thr Ser Arg Arg Xaa 85 90 95 Arg Arg Xaa Xaa Gly Arg Gly Asp Val Thr 100 105 45 141 PRT Trypanosoma cruzi 45 Ser Ile Pro Val Glu Ile Asp Ile Arg Asn Gln Asp Phe Ser Phe Leu 1 5 10 15 Asp Pro Ala Pro Glu Gly Ile Pro Ile Gln Asp Ile His Leu Met Gly 20 25 30 Asp Ser Ala Phe Ala Ala Ser Ala Arg Glu Arg Met Lys Leu Lys Arg 35 40 45 Asn Pro Val Ala Asn Ala Ser Lys Ile Ser Ala Leu Glu Glu Glu Met 50 55 60 Asp Gln Arg Ala His Val Leu Ala Lys Gln Val Arg Asp Lys Glu Arg 65 70 75 80 Thr Phe Leu Asp Pro Glu Pro Glu Gly Val Pro Leu Glu Leu Leu Ser 85 90 95 Leu Asn Glu Asn Glu Ala Ser Gln Glu Leu Glu Arg Glu Leu Arg Ala 100 105 110 Leu Asn Arg Lys Pro Arg Lys Asp Ala Lys Ala Ile Val Ala Leu Glu 115 120 125 Asp Asp Val Arg Asp Glu His Thr Cys Leu Pro Arg Ser 130 135 140 46 27 PRT Trypanosoma cruzi 46 Arg Lys Met Ser Gly Thr Ser Leu Leu Ala Pro Gln Pro Glu Gly Val 1 5 10 15 Pro Val Ser Glu Leu Ser Leu Asp Leu Asp Glu 20 25 47 117 PRT Trypanosoma cruzi 47 Leu Leu Ala Leu Leu Gln Gly Leu Val Gln Leu Arg Thr Gln Ile His 1 5 10 15 Gly Val Arg Pro Ala Leu Leu Pro Glu Ser Gly Gln Phe Leu Gly Gly 20 25 30 Ser Leu Gln Leu Ala Met His Leu Leu Ala Leu Leu Gln Gly Leu Val 35 40 45 Gln Leu Arg Thr Gln Ile His Gly Val Arg Pro Ala Leu Leu Pro Glu 50 55 60 Ser Gly Gln Phe Leu Gly Gly Ser Leu Gln Leu Ala Met His Leu Leu 65 70 75 80 Ala Leu Leu Gln Gly Leu Val Gln Leu Arg Thr Gln Ile His Gly Val 85 90 95 Arg Pro Ala Leu Leu Pro Glu Ser Gly Gln Phe Leu Gly Gly Ser Leu 100 105 110 Gln Leu Ala Thr His 115 48 117 PRT Trypanosoma cruzi 48 Ser Ser Arg Cys Cys Lys Ala Ser Ser Ser Cys Ala Arg Arg Phe Thr 1 5 10 15 Val Ser Ala Pro Leu Cys Ser Arg Arg Ala Ala Ser Ser Ser Val Val 20 25 30 Arg Phe Ser Ser Arg Cys Thr Ser Ser Arg Cys Cys Lys Ala Ser Ser 35 40 45 Ser Cys Ala Arg Arg Phe Thr Val Ser Ala Pro Leu Cys Ser Arg Arg 50 55 60 Ala Gly Ser Ser Ser Val Val Arg Phe Ser Ser Arg Cys Thr Ser Ser 65 70 75 80 Arg Cys Cys Lys Ala Ser Ser Ser Cys Ala Arg Arg Phe Thr Val Ser 85 90 95 Ala Pro Leu Cys Ser Arg Arg Ala Gly Ser Ser Ser Val Val Arg Phe 100 105 110 Ser Ser Arg Arg Thr 115 49 117 PRT Trypanosoma cruzi 49 Pro Pro Arg Ala Ala Ala Arg Pro Arg Pro Ala Ala His Ala Asp Ser 1 5 10 15 Arg Cys Pro Pro Arg Ser Ala Pro Gly Glu Arg Pro Val Pro Arg Trp 20 25 30 Phe Ala Ser Ala Arg Asp Ala Pro Pro Arg Ala Ala Ala Arg Pro Arg 35 40 45 Pro Ala Ala His Ala Asp Ser Arg Cys Pro Pro Arg Ser Ala Pro Gly 50 55 60 Glu Arg Ala Val Pro Arg Trp Phe Ala Ser Ala Arg Asp Ala Pro Pro 65 70 75 80 Arg Ala Ala Ala Arg Pro Arg Pro Ala Ala His Ala Asp Ser Arg Cys 85 90 95 Pro Pro Arg Ser Ala Pro Gly Glu Arg Ala Val Pro Arg Trp Phe Ala 100 105 110 Ser Ala Arg Asp Ala 115 50 207 PRT Trypanosoma cruzi 50 Ala Glu Pro Lys Pro Ala Glu Pro Lys Ser Ala Glu Pro Lys Pro Ala 1 5 10 15 Glu Pro Lys Ser Ala Glu Pro Lys Pro Ala Glu Pro Lys Ser Ala Glu 20 25 30 Pro Lys Pro Ala Glu Pro Lys Ser Ala Gly Pro Lys Pro Ala Glu Pro 35 40 45 Lys Ser Ala Glu Pro Lys Pro Ala Glu Pro Lys Ser Ala Glu Pro Lys 50 55 60 Pro Ala Glu Pro Lys Ser Ala Glu Pro Lys Pro Ala Glu Pro Lys Ser 65 70 75 80 Ala Glu Pro Lys Pro Ala Glu Ser Lys Ser Ala Glu Pro Lys Pro Ala 85 90 95 Glu Pro Lys Ser Ala Glu Pro Lys Pro Ala Glu Ser Lys Ser Ala Glu 100 105 110 Pro Lys Pro Ala Glu Pro Lys Ser Ala Glu Pro Lys Pro Ala Glu Pro 115 120 125 Lys Ser Ala Glu Pro Lys Pro Ala Glu Pro Lys Ser Ala Glu Pro Lys 130 135 140 Pro Ala Glu Pro Lys Ser Ala Glu Pro Lys Pro Ala Glu Ser Lys Ser 145 150 155 160 Ala Gly Pro Lys Pro Ala Glu Pro Lys Ser Ala Glu Pro Lys Pro Ala 165 170 175 Glu Pro Lys Ser Ala Glu Pro Lys Pro Ala Glu Pro Lys Ser Ala Glu 180 185 190 Pro Lys Pro Ala Glu Pro Lys Ser Ala Glu Pro Lys Pro Ala Glu 195 200 205 51 263 PRT Trypanosoma cruzi Where any Xaa is an independently selected amino acid 51 Arg Arg Gly Tyr Pro Arg Ser Arg Met Pro Ser Lys Glu Leu Trp Met 1 5 10 15 Arg Arg Leu Arg Ile Leu Arg Arg Leu Leu Arg Lys Tyr Arg Glu Glu 20 25 30 Lys Lys Ile Asp Arg His Ile Tyr Arg Glu Leu Tyr Val Lys Ala Lys 35 40 45 Gly Asn Val Phe Arg Asn Lys Arg Asn Leu Met Glu His Ile His Lys 50 55 60 Val Lys Asn Glu Lys Lys Lys Glu Arg Gln Leu Ala Glu Gln Leu Ala 65 70 75 80 Ala Asn Ala Xaa Lys Asp Glu Gln His Arg His Lys Ala Arg Lys Gln 85 90 95 Glu Leu Arg Lys Arg Glu Lys Asp Arg Glu Arg Ala Arg Arg Glu Asp 100 105 110 Ala Ala Ala Ala Ala Ala Ala Lys Gln Lys Ala Ala Ala Lys Lys Ala 115 120 125 Ala Ala Pro Ser Gly Lys Lys Ser Ala Lys Ala Ala Ile Ala Pro Ala 130 135 140 Lys Ala Ala Ala Ala Pro Ala Lys Ala Ala Ala Ala Pro Ala Lys Ala 145 150 155 160 Ala Ala Ala Pro Ala Lys Ala Ala Ala Ala Pro Ala Lys Ala Ala Ala 165 170 175 Ala Pro Ala Lys Ala Ala Thr Ala Pro Ala Lys Ala Ala Ala Ala Pro 180 185 190 Ala Lys Thr Ala Ala Ala Pro Ala Lys Ala Ala Ala Pro Ala Lys Ala 195 200 205 Ala Ala Ala Pro Ala Lys Ala Ala Thr Ala Pro Ala Lys Ala Ala Ala 210 215 220 Ala Pro Ala Lys Ala Ala Thr Ala Pro Ala Lys Ala Ala Thr Ala Pro 225 230 235 240 Ala Lys Ala Ala Ala Ala Pro Ala Lys Ala Ala Thr Ala Pro Val Gly 245 250 255 Lys Lys Ala Gly Gly Lys Lys 260 52 442 PRT Trypanosoma cruzi 52 Asp Phe Ile Trp Tyr Lys Val Val Ala Leu Leu Val Val Ile Thr Ser 1 5 10 15 Asn Gly Asp Asp Val Ser Val Tyr Thr Ala Thr Ile Lys Glu Phe Tyr 20 25 30 Arg Tyr Leu Trp Ile Phe Val Pro Val Ser Leu Phe Ser Ile Ile Ile 35 40 45 Tyr Phe Val Ser Ile Phe Cys Phe Pro Ala Ser Tyr Gly Leu Phe Phe 50 55 60 Ser Ser Phe Leu Lys Phe Gln Leu Leu Leu Asn His Lys His Pro Val 65 70 75 80 Leu Gln Pro Pro His Gln Met Val Ser Leu Lys Leu Gln Ala Arg Leu 85 90 95 Ala Ala Asp Ile Leu Arg Cys Gly Arg His Arg Val Trp Leu Asp Pro 100 105 110 Asn Glu Ala Ser Glu Ile Ser Asn Ala Asn Ser Arg Lys Ser Val Arg 115 120 125 Lys Leu Ile Lys Asp Gly Leu Ile Ile Arg Lys Pro Val Lys Val His 130 135 140 Ser Arg Ser Arg Trp Arg His Met Lys Glu Ala Lys Ser Met Gly Arg 145 150 155 160 His Glu Gly Ala Gly Arg Arg Glu Gly Thr Arg Glu Ala Arg Met Pro 165 170 175 Ser Lys Glu Leu Trp Met Arg Arg Leu Arg Ile Leu Arg Arg Leu Leu 180 185 190 Arg Lys Tyr Arg Glu Glu Lys Lys Ile Asp Arg His Ile Tyr Arg Glu 195 200 205 Leu Tyr Val Lys Ala Lys Gly Asn Val Phe Arg Asn Lys Arg Asn Leu 210 215 220 Met Glu His Ile His Lys Val Lys Asn Glu Lys Lys Lys Glu Arg Gln 225 230 235 240 Leu Ala Glu Gln Leu Ala Ala Lys Arg Leu Lys Asp Glu Gln His Arg 245 250 255 His Lys Ala Arg Lys Gln Glu Leu Arg Lys Arg Glu Lys Asp Arg Glu 260 265 270 Arg Ala Arg Arg Glu Asp Ala Ala Ala Ala Ala Ala Ala Lys Gln Lys 275 280 285 Ala Ala Ala Lys Lys Ala Ala Ala Pro Ser Gly Lys Lys Ser Ala Lys 290 295 300 Ala Ala Ala Pro Ala Lys Ala Ala Ala Ala Pro Ala Lys Ala Ala Ala 305 310 315 320 Pro Pro Ala Lys Thr Ala Ala Ala Pro Ala Lys Ala Ala Ala Pro Ala 325 330 335 Lys Ala Ala Ala Pro Pro Ala Lys Ala Ala Ala Pro Pro Ala Lys Thr 340 345 350 Ala Ala Pro Pro Ala Lys Thr Ala Ala Pro Pro Ala Lys Ala Ala Ala 355 360 365 Pro Pro Ala Lys Ala Ala Ala Pro Pro Ala Lys Ala Ala Ala Pro Pro 370 375 380 Ala Lys Ala Ala Ala Ala Pro Ala Lys Ala Ala Ala Ala Pro Ala Lys 385 390 395 400 Ala Ala Ala Pro Pro Ala Lys Ala Ala Ala Pro Pro Ala Lys Ala Ala 405 410 415 Ala Pro Pro Ala Lys Ala Ala Ala Pro Pro Ala Lys Ala Ala Ala Ala 420 425 430 Pro Val Gly Lys Lys Ala Gly Gly Lys Lys 435 440 53 15 PRT Artificial Sequence Description of Artificial Sequence TcD antigenic epitope 53 Ala Glu Pro Lys Ser Ala Glu Pro Lys Pro Ala Glu Pro Lys Ser 1 5 10 15 54 15 PRT Artificial Sequence Description of Artificial Sequence TcD antigenic epitope 54 Ala Glu Pro Lys Pro Ala Glu Pro Lys Ser Ala Glu Pro Lys Pro 1 5 10 15 55 21 PRT Artificial Sequence Description of Artificial Sequence TcE antigenic epitope 55 Lys Ala Ala Ile Ala Pro Ala Lys Ala Ala Ala Ala Pro Ala Lys Ala 1 5 10 15 Ala Thr Ala Pro Ala 20 56 21 PRT Artificial Sequence Description of Artificial Sequence TcE antigenic epitope 56 Lys Ala Ala Ala Ala Pro Ala Lys Ala Ala Ala Ala Pro Ala Lys Ala 1 5 10 15 Ala Ala Ala Pro Ala 20 57 22 PRT Artificial Sequence Description of Artificial Sequence PEP2 antigenic epitope 57 Gly Asp Lys Pro Ser Pro Phe Gly Gln Ala Ala Ala Gly Asp Lys Pro 1 5 10 15 Ser Pro Phe Gly Gln Ala 20 58 21 PRT Artificial Sequence Description of Artificial Sequence TcE antigenic epitope 58 Lys Ala Ala Ala Ala Pro Ala Lys Ala Ala Ala Ala Pro Ala Lys Ala 1 5 10 15 Ala Ala Ala Pro Ala 20 59 21 PRT Artificial Sequence Description of Artificial Sequence TcE antigenic epitope 59 Lys Ala Ala Thr Ala Pro Ala Lys Ala Ala Thr Ala Pro Ala Lys Ala 1 5 10 15 Ala Thr Ala Pro Ala 20 60 21 PRT Artificial Sequence Description of Artificial Sequence TcE antigenic epitope 60 Lys Ala Ala Ile Ala Pro Ala Lys Ala Ala Ile Ala Pro Ala Lys Ala 1 5 10 15 Ala Ile Ala Pro Ala 20 61 14 PRT Artificial Sequence Description of Artificial Sequence TcE antigenic epitope 61 Lys Ala Ala Ala Ala Pro Ala Lys Ala Ala Ala Ala Pro Ala 1 5 10 62 14 PRT Artificial Sequence Description of Artificial Sequence TcE antigenic epitope 62 Lys Ala Ala Ala Ala Pro Ala Lys Ala Ala Thr Ala Pro Ala 1 5 10 63 83 PRT Artificial Sequence Description of Artificial Sequence Tetrapeptide containing four immunoreactive T. cruzi epitopes PEP-2, TcD, TcE and TcLo1.2 in a linear sequence 63 Gly Asp Lys Pro Ser Pro Phe Gly Gln Ala Ala Ala Gly Asp Lys Pro 1 5 10 15 Ser Pro Phe Gly Gln Ala Gly Cys Gly Ser Ser Met Pro Ser Gly Thr 20 25 30 Ser Glu Glu Gly Ser Arg Gly Gly Ser Ser Met Pro Ala Gly Cys Gly 35 40 45 Lys Ala Ala Ala Ala Pro Ala Lys Ala Ala Ala Ala Pro Ala Gly Cys 50 55 60 Gly Ala Glu Pro Lys Ser Ala Glu Pro Lys Pro Ala Glu Pro Lys Ser 65 70 75 80 Gly Cys Gly 64 21 PRT Artificial Sequence Description of Artificial Sequence TcHi29 antigenic epitope 64 Lys Thr Ala Ala Pro Pro Ala Lys Thr Ala Ala Pro Pro Ala Lys Thr 1 5 10 15 Ala Ala Pro Pro Ala 20 65 618 PRT Trypanosoma cruzi 65 Lys Ala Val Asp Pro Phe Gln Gly Thr Thr Pro Pro Pro Tyr Lys Trp 1 5 10 15 Gln Glu Met Thr Gly Ser Glu Ala Ala Ala Gly Ser Leu Cys Val Pro 20 25 30 Ser Leu Ala Glu Val Ala Gly Gly Val Phe Ala Val Ala Glu Ala Gln 35 40 45 Arg Ser Glu Arg Asp Glu Ala Cys Gly His Ala Ala Ile Ala Thr Thr 50 55 60 His Ile Glu Thr Gly Gly Gly Gly Ser Lys Ala Ile Ser Ala Met Asp 65 70 75 80 Ala Gly Val Phe Leu Val Glu Leu Val Asp Ala Ala Ser Gly Thr Ile 85 90 95 Arg Thr Arg Glu Lys Met Gln Pro Thr Thr Ile Val Ser Gly Asp Thr 100 105 110 Ile Tyr Met Ala Leu Gly Asp Tyr Glu Lys Lys Thr Ser Gly Gly Arg 115 120 125 Ala Ala Asp Ala Asp Gly Trp Arg Leu Leu Leu Met Arg Gly Thr Leu 130 135 140 Thr Glu Asp Gly Gly Gln Lys Lys Ile Met Trp Gly Asp Ile Arg Ala 145 150 155 160 Val Asp Pro Val Ala Ile Gly Leu Thr Gln Phe Leu Lys Arg Val Ile 165 170 175 Gly Gly Gly Gly Ser Gly Val Val Thr Lys Asn Gly Tyr Leu Val Leu 180 185 190 Pro Met Gln Ala Val Glu Lys Asp Gly Arg Ser Val Val Leu Ser Met 195 200 205 Arg Phe Asn Met Arg Ile Glu Ala Cys Glu Leu Ser Ser Gly Thr Thr 210 215 220 Gly Ser Asn Cys Lys Glu Pro Ser Ile Ala Asn Leu Glu Gly Asn Leu 225 230 235 240 Ile Leu Ile Thr Ser Cys Ala Ala Gly Tyr Tyr Glu Val Phe Arg Ser 245 250 255 Leu Asp Ser Gly Thr Ser Trp Glu Met Ser Gly Arg Pro Ile Ser Arg 260 265 270 Val Trp Gly Asn Ser Tyr Gly Arg Lys Gly Tyr Gly Val Arg Cys Gly 275 280 285 Leu Thr Thr Val Thr Ile Glu Gly Arg Glu Val Leu Leu Val Thr Thr 290 295 300 Pro Val Tyr Leu Glu Glu Lys Asn Gly Arg Gly Arg Leu His Leu Trp 305 310 315 320 Val Thr Asp Gly Ala Arg Val His Asp Ala Gly Pro Ile Ser Asp Ala 325 330 335 Ala Asp Asp Ala Ala Ala Ser Ser Leu Leu Tyr Ser Ser Gly Gly Asn 340 345 350 Leu Ile Ser Leu Tyr Glu Asn Lys Ser Glu Gly Ser Tyr Gly Leu Val 355 360 365 Ala Val His Val Thr Thr Gln Leu Glu Arg Ile Lys Thr Val Leu Lys 370 375 380 Arg Trp Gln Glu Leu Asp Glu Ala Leu Arg Thr Cys Arg Ser Thr Ala 385 390 395 400 Thr Ile Asp Pro Val Arg Arg Gly Met Cys Ile Arg Pro Ile Leu Thr 405 410 415 Asp Gly Leu Val Gly Tyr Leu Ser Gly Leu Ser Thr Gly Ser Glu Trp 420 425 430 Met Asp Glu Tyr Leu Cys Val Asn Ala Thr Val His Gly Thr Val Arg 435 440 445 Gly Phe Ser Asn Gly Val Thr Phe Glu Gly Pro Gly Ala Gly Ala Gly 450 455 460 Trp Pro Val Ala Arg Ser Gly Gln Asn Gln Pro Tyr His Phe Leu His 465 470 475 480 Lys Thr Phe Thr Leu Val Val Met Ala Val Ile His Asp Arg Pro Lys 485 490 495 Lys Arg Thr Pro Ile Pro Leu Ile Arg Val Val Met Asp Asp Asn Asp 500 505 510 Lys Thr Val Leu Phe Gly Val Phe Tyr Thr His Asp Gly Arg Trp Met 515 520 525 Thr Val Ile His Ser Gly Gly Arg Gln Ile Leu Ser Thr Gly Trp Asp 530 535 540 Pro Glu Lys Pro Cys Gln Val Val Leu Arg His Asp Thr Gly His Trp 545 550 555 560 Asp Phe Tyr Val Asn Ala Arg Lys Ala Tyr Phe Gly Thr Tyr Lys Gly 565 570 575 Leu Phe Ser Lys Gln Thr Val Phe His Thr Ser Asn Ser Thr Gly Arg 580 585 590 Val Gly Lys Leu Gln Ser Pro Ala Ile Cys His Ser Ser Thr Pro Val 595 600 605 Cys Ile Thr Glu Asp Ser Ile Pro Ser Ile 610 615 66 39 DNA Trypanosoma cruzi 66 ggggacaaac cgtctccgtt ccaggctgct gctggtgac 39 67 49 DNA Trypanosoma cruzi 67 gagacggttt gtcaccagca gcagcctgga acggagacgg tttgtcccc 49 68 40 DNA Trypanosoma cruzi 68 aaaccgtctc cgttcggtca ggctgctgaa ccgaaatctg 40 69 40 DNA Trypanosoma cruzi 69 ttcggttcag cagatttcgg ttcagcagcc tgaccgaacg 40 70 51 DNA Trypanosoma cruzi 70 ctgaaccgaa accggctgaa ccgaaaagcg ctctagatgc atgaattcca g 51 71 41 DNA Trypanosoma cruzi 71 ctggaattca tgcatctaga gcgcttttcg gttcagccgg t 41 72 49 DNA Trypanosoma cruzi 72 aaagctgcta tcgctccggc taaagctgct gctgctccgg ctaaagctg 49 73 39 DNA Trypanosoma cruzi 73 cggagcagca gcagctttag ccggagcgat agcagcttt 39 74 29 DNA Trypanosoma cruzi 74 ctaccgctcc ggccggctcg agatgcatg 29 75 43 DNA Trypanosoma cruzi 75 aattcatgca tctcgagccg gccggagcgg tagcagcttt agc 43 76 49 DNA Trypanosoma cruzi 76 tcttctatgc cgtctggtac ctctgaagaa ggttctcgtg gtggttctt 49 77 39 DNA Trypanosoma cruzi 77 acgagaacct tcttcagagg taccagacgg catagaaga 39 78 26 DNA Trypanosoma cruzi 78 ctatgccggc cggctcgaga tgcatg 26 79 40 DNA Trypanosoma cruzi 79 aattcatgca tctcgagccg gccggcatag aagaaccacc 40 80 23 DNA Trypanosoma cruzi 80 ataccccggg gacaaccgtc tcc 23 81 26 DNA Trypanosoma cruzi 81 cgccttagcc tggaattcat gcatct 26 82 85 PRT Trypanosoma cruzi 82 Met Gly His His His His His His Gly Asp Lys Pro Ser Pro Phe Gln 1 5 10 15 Ala Ala Ala Gly Asp Lys Pro Ser Pro Phe Gly Gln Ala Ala Glu Pro 20 25 30 Lys Ser Ala Glu Pro Lys Pro Ala Glu Pro Lys Ser Lys Ala Ala Ile 35 40 45 Ala Pro Ala Lys Ala Ala Ala Ala Pro Ala Lys Ala Ala Thr Ala Pro 50 55 60 Ala Ser Ser Met Pro Ser Gly Thr Ser Glu Glu Gly Ser Arg Gly Gly 65 70 75 80 Ser Ser Met Pro Ala 85 83 49 DNA Artificial Sequence Made in laboratory 83 aaaccgtctc cgttcggtca ggctggttgt ggtgctgaac cgaaatctg 49 84 49 DNA Artificial sequence Made in laboratory 84 ttcggttcag cagatttcgg ttcagcacca caaccagcct gaccgaacg 49 85 43 DNA Artificial Sequence Made in laboratory 85 ctgaaccgaa accggctgaa ccgaaaagcg ctctagatgc atg 43 86 37 DNA Artificial Sequence Made in laboratory 86 aattcatgca tctagagcgc ttttcggttc agccggt 37 87 49 DNA Artificial Sequence Made in laboratory 87 ggttgtggta aagctgctat cgctccggct aaagctgctg ctgctccgg 49 88 39 DNA Artificial Sequence Made in laboratory 88 agcagcttta gccggagcga tagcagcttt accacaacc 39 89 38 DNA Artificial Sequence Made in laboratory 89 ctaaagctgc taccgctccg gccggctcga gatgcatg 38 90 52 DNA Artificial Sequence Made in laboratory 90 aattcatgca tctcgagccg gccggagcgg tagcagcttt agccggagca gc 52 91 44 DNA Artificial Sequence Made in laboratory 91 ggttgtggtt cttctatgcc gtctggtacc tctgaagaag gttc 44 92 34 DNA Artificial Sequence Made in laboratory 92 cagaggtacc agacggcata gaagaaccac aacc 34 93 27 DNA Artificial Sequence Made in laboratory 93 tcgtggtggt tcttctatgc cggcctg 27 94 41 DNA Artificial Sequence Made in laboratory 94 aattcaggcc ggcatagaag aaccaccacg agaaccttct t 41 95 94 PRT Trypanosoma cruzi 95 Met Gly His His His His His His Gly Asp Lys Pro Ser Pro Phe Gln 1 5 10 15 Ala Ala Ala Gly Asp Lys Pro Ser Pro Phe Gly Gln Ala Gly Cys Gly 20 25 30 Ala Glu Pro Lys Ser Ala Glu Pro Lys Pro Ala Glu Pro Lys Ser Gly 35 40 45 Cys Gly Lys Ala Ala Ile Ala Pro Ala Lys Ala Ala Ala Ala Pro Ala 50 55 60 Lys Ala Ala Thr Ala Pro Ala Gly Cys Gly Ser Ser Met Pro Ser Gly 65 70 75 80 Thr Ser Glu Glu Gly Ser Arg Gly Gly Ser Ser Met Pro Ala 85 90 

What is claimed is:
 1. A combination polypeptide comprising at least two amino acid sequences, wherein at least one of the amino acid sequences comprises SEQ ID NO:35.
 2. A combination polypeptide comprising SEQ ID NO:35, wherein the combination polypeptide further comprises SEQ ID NO:82.
 3. A combination polypeptide comprising SEQ ID NO:35, wherein the combination polypeptide further comprises SEQ ID NO:95.
 4. A combination polypeptide according to claim 1, wherein the combination polypeptide is prepared using recombinant DNA technology.
 5. A combination polypeptide according to claim 1, wherein the combination polypeptide is prepared synthetically.
 6. A combination polypeptide according to claim 1, further comprising the sequence of SEQ ID NO:53.
 7. A combination polypeptide according to claim 1, further comprising the sequence of SEQ ID NO:55.
 8. A combination polypeptide according to claim 1, further comprising the sequence of SEQ ID NO:57. 